Dynamics Magazine 1201 by CD-adapco

issue 12.01

rise of the electric machine

Features

InDesA Virtual Test Center

ELECTRONICS DESIGN Pushing the Boundaries

CHASING THE WIND Americaâ&#x20AC;&#x2122;s Cup Design

LEARJET 60 Designing a Drag-Free Locker

Contents Introduction 03 CD-adapco Meets the Electric Machine Introduction by Tim Miller

Breaking News • STAR-Cast • New Offices • Olin College HPV

• DARS • STAR-CD and ES-ICE v4.16 • Pace Formula One

• STAR-CCM+ v6.06 • Panther Racing

ELECTRIC MACHINES A New, Groundbreaking Tool to Simulate Batteries Interview with Steve Hartridge

Electromagnetic Capabilities Breaking New Ground with STAR-CCM+

17 Rise of the (Electric) Machines:

CD-adapco & the Need for SPEED

ELECTRonics 19 Pushing the Boundaries Electronics Design

Is your Electronics Cooling Software Fit for Purpose? Electronics Cooling

AUTOMOTIVE Virtual Testing InDesA Virtual Test Facility Center

27 31

Sunroof Buffeting A New Fluid-Structure Integrated Capability for Aeroacoustics Simulations

35 CFD Helps to Make Engines More Efficient

Combustion Simulations with STAR-CD

TURBOMACHINERY 37 Turbocharger Analysis Thermo-Fluid-Structural Solutions using STAR-CCM+

39 NASA C3X Turbine

Polyhedral Meshing & Transition Modeling

Harmonic Balance Method A Break From Traditional Simulation of Turbomachinery Flows

AEROSPACE 43 Designing a Drag-Free Storage Locker for the Learjet 60 Raisbeck Engineering showcase their in-house CFD capability

From Design Challenge to Flying UAV’s in Fifteen Weeks University of Washington’s Capstone Project

Oil AND GAS

51 Deepwater Flow Assurance

Integration of 1D & 3D Flow Simulation

MARINE 55 Chasing The Wind The New State-of-the-Art in the America’s Cup Design Regulars 59 Dr Mesh 61 • Training

• Global Events

EDITORIAL Dynamics welcomes editorial from all users of CD-adapco software or services. To submit an article, email: editorial@cd-adapco.com Telephone: +44 (0)20 7471 6200 Editor Assistant Editor Associate Editors Design & Art Direction e-dynamics Advertising Sales US Events European Events

Stephen Ferguson - stephen.ferguson@cd-adapco.com Deborah Eppel - deborah.eppel@cd-adapco.com Prashanth Shankara - prashanth.shankara@cd-adapco.com Lauren Gautier - lauren.gautier@cd-adapco.com Brandon Botha - brandon.botha@cd-adapco.com Mathew Parry - mat.parry@cd-adapco.com Geri Jackman - geri.jackman@cd-adapco.com Tara Firenze - tara.firenze@cd-adapco.com Sandra Maureder - sandra.maureder@cd-adapco.com

Subscriptions & DIGITAL EDITIONS Dynamics is published approximately twice a year, and distributed internationally. All recent editions of Dynamics, Special Reports & Digital Reports are now available online: www.cd-adapco.com/press_room/dynamics We also produce our monthly e-dynamics newsletter which is available on subscription. To subscribe or unsubscribe to Dynamics and e-dynamics, please email info@cd-adapco.com To advertise in Dynamics magazine or e-dynamics, please download our media kit online: www.cd-adapco.com/products/brochures/dynamics/mediakit.pdf

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United States New York • Headquarters 60 Broadhollow Road Melville, NY 11747, USA Tel.: (+1) 631 549 2300 Austin TX Cincinnati OH Detroit MI Houston TX Lebanon NH Los Angeles CA Seattle WA State College PA Tulsa OK South America São Paulo, Brazil

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India: Bangalore Japan: Yokohama, Osaka Korea: Seoul Singapore: Singapore All inquiries, please contact: info@cd-adapco.com

RECYCLED PAPER. VEGETABLE INKS.

Resellers Australia CD-adapco Australia info-au@cd-adapco.com Israel ADCOM Consulting Services (Shmulik Keidar Ltd.) info@adcomsim.co.il New Zealand Matrix Applied Computing Ltd. sales@matrix.co.nz

Russia SAROV Engineering Center info@saec.ru South Africa Aerotherm Computational Dynamics martin@aerothermcd.co.za Turkey A-Ztech Ltd. info@a-ztech.com.tr

China CDAJ-China info@cdaj-china.com Japan CDAJ Japan info@cdaj.co.jp

..::INTRODUCTION Tim Miller

The cost of energy has always motivated the development of electric machine design, but today the twin monsters of unbridled consumer demand and scarcity of required materials makes it ever more important to optimize designs with better analytical tools.

CD-adapco Meets the Electric Machine Introduction by Tim Miller Civilization as we know it is utterly dependent on electricity, most of which is generated in thermal power stations by large rotating machines. About 60% of all electric energy is used in electric motors driving pumps, fans, and compressors not seen by the general public. Without them we would have no water and no waste treatment. No machinery, no clothing, no transport, and no food. Without electric generators and motors, we would be set back to the 19th century. The electrification of the industrialized world is accelerating. The number of electric motors used in a single house may easily exceed 50. Count them in your own house. If you find fewer than 10, you haven’t looked hard enough. Similarly automobiles, aircraft, railway locomotives and all forms of special vehicles rely on more and more electric motors for auxiliary functions and traction. And in factories and offices the motor population is gigantic. Unless you are reading this out in the woods somewhere, you can probably hear an electric motor right now (or more likely, the fan or compressor it is driving). By far the greatest number of electric motors are the AC induction motor and the DC commutator motor. There are also some specialty motors such as brushless permanent-magnet motors used in a wide range of applications such as small fans and industrial motion control. Highlypublicized electric and hybrid vehicles often use this type of machine, although this could change quickly and dramatically because of rapid increases in magnet costs. Electric vehicles account for an insignificant proportion of energy usage, and it is important not to be carried away by the glitzy advertising: most of the world’s electrical energy is used up in those lowly workhorse applications, not in the dream cars of the future. The cost of energy has always motivated the development of electric machine design, but today the twin monsters of unbridled consumer demand and scarcity of required materials makes it ever more important to optimize designs with better analytical tools. The SPEED software recently purchased by CD-adapco has been in the business of electric

i FOR more infoRMATION EMAIL: tim.miller@cd-adapco.com

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machine design for a quarter of a century, and is used in thousands of products. Based on the deep underlying theory of the electrical machine, it calculates almost all aspects of design in a highly efficient way. Because of its speed of execution there is practically no waiting time for the designer, a critical requirement in assuring design productivity. SPEED is capable of contributing geometry and heat loads to STAR-CCM+ for more intense analysis of heat transfer and fluid flow. Eventually there may be a capability for electromagnetic calculations that would extend SPEED’s accuracy in dealing with three-dimensional effects and eddy-current effects that cause parasitic losses. In the next few months it will be interesting to see how this develops. But however it turns out, CD-adapco has certainly come face to face with the electrical world. Tim Miller Consultant to CD-adapco, SPEED & STAR-CCM+ Design of Electrical Machines

..::INTRODUCTION Breaking News Follow the latest breaking news online:

www.cd-adapco.com/news

STAR-Cast v1.10: Industrial Strength Casting Simulation for Foundrymen, Designers and Toolmakers CD-adapco and Access are pleased to announce the release of an exciting new version of STAR-Cast, the technology-leading simulation tool for all industrial casting simulations. Developed in collaboration between a world-leading provider of engineering simulation technology and recognized international experts in casting and metallurgy, STAR-Cast v1.10 brings automation and ease-of-use into casting and foundry processes. STAR-Cast provides a comprehensive and intuitive process for performing multiphase casting simulation – liquid, solid and gaseous – including conjugate heat transfer, a sharp resolution of the filling front, free-surface fragmentation, motion of trapped gas bubbles in melt, and natural convection in melt and gas. “STAR-Cast v1.10 includes a new streamlined casting simulation process that places industrial strength simulation technology in the hands of foundrymen, casting designers and tool makers,” says Robert Guntlin, Managing Director of Access. “The addition of new tools that facilitate High Pressure Die Casting and Investment Casting makes STAR-Cast v1.10 a formidable tool that I sincerely believe will lead to unprecedented levels of innovation and cost reduction in industrial casting.” “CD-adapco is committed to making the best advanced engineering simulation technology available for solving the most difficult problems that manufacturing has to offer,” said CD-adapco President Steve MacDonald. “STAR-Cast v1.10 is a product of our many years of simulation experience combined with the leading expertise of Acces in casting and metallurgy. We are proud to be their partners.”

STAR-Cast v1.10 is now also available on the Windows 7.0 platform. Enhancements to STAR-Cast v1.10 include: High Pressure Die Casting: STAR-Cast v1.10 includes the ability to simulate the action of a moving piston, facilitating the analysis of High Pressure Die Casting (HPDC) processes. Shell Molds for Investment Casting: Realistic modeling of dipping-type ceramic shell molds is crucial to accurate simulation of investment casting processes. STAR-Cast v1.10 provides a high-performance tool for calculating the outer surface of the virtual shell in close correlation to the real shape of the mold. Investment Casting Misrun Prediction: The prediction of misrun formation is based on STAR-Cast’s unique, fully coupled computational continuum mechanics approach, featuring a multiphase mold filling module. Material Database: The precision of casting simulation results depends to a high degree on the quality and completeness of the required material data. For this reason, STAR-Cast offers a dedicated material database,STAR-Cast mat, whose data are certified and qualified according to an internal documentation scheme.

i VISIT THE NEW STAR-CAST WEBSITE: www.star-cast.com

Introducing DARS v2.06: Advanced Chemistry Simulation for Efficient & Green Engineering DigAnaRS is pleased to announce the launching of DARS v2.06, the latest release of their advanced simulation tool for the analysis of complex chemical reactions. The latest version includes an improved user interface, significantly reduced simulation times and improved predictive capabilities.

DARS 2.06 was officially launched at the STAR European Conference 2011, presentations and demonstrations that explore all of the new features are available. DARS V2.06 is now available for CD-adapco customers to use.

“From the very beginning our intention was to make DARS the easiest and most accessible simulation tool for understanding and optimizing devices that feature complex chemical reactions. With the release of DARS v2.06 we have finally realized that ambition” says Fabian Mauss, President and Founder of DigAnaRS. “DARS v2.06 provides users from the automotive, energy and chemical industries with an intuitive and flexible analytic toolkit required to develop more environmentally considerate products in less time than ever before.” DARS v2.06 sets new standards in the modeling catalytic converters, including particulate filters. Combined with the predictive reactor and engine models DARS v2.06 also enables the optimization of processes. Kinetic mapping gives users insight into how process parameters influence process efficiency and emission. DARS provides you the tools that explain your results to your colleagues.

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i FOR more infoRMATION: www.diganars.com

..::INTRODUCTION Breaking News

Now Available!

ABOVE Vehicle soiling simulation using liquid film stripping

STAR-CCM+ v6.06: Faster, Better, and Wider CD-adapco is pleased to announce the release of STAR-CCM+ v6.06, CD-adapco’s simulation software for solving multidisciplinary engineering problems. “Released three times a year, each new version of STAR-CCM+ is focused on improving customer satisfaction,” says Senior VP of Product Management Jean-Claude Ercolanelli. “We set ourselves a very high standard in this regard and our success is confirmed by our users: in our annual 2011 customer survey, 97% of CD-adapco users said that they would recommend our software.” STAR-CCM+ v6.06 ensures higher throughput and offers: FASTER turnaround times: support of parallel I/O file systems, new sparse solver for electrical solutions, quicker polyhedral meshing, and new CAD reading technology; BETTER application coverage: improved process for Li-ion batteries simulation, new physical models for Eulerian multiphase flow and LES combustion; WIDER multidisciplinary solution: simulation of electromagnetics and electrical fields, and import of SPEED models for flow and thermal analyses of electrical devices. Improvements to the User Environment Optimizing License Resources: a new flexible licensing approach is adopted, meaning that users can take, reserve, or release licenses for add-on modules (such as Battery Simulation Module, DARS-CFD, JTOpen Reader, and CAD Exchange Reader) from within their working session. Geometry Preparation and Surface Meshing CAD Clients: Live Model Checker provides feedback of model validity during the setup process, checking for consistency and conflicts. Upfront flow and thermal simulations can also be run in parallel from within your CAD environment.

Engineering Physics SPEED Integration: directly import models from CD-adapco’s new electric machines tool and generate a 3D analysis-ready STAR-CCM+ model. Thermal fields can be transferred onto the imported geometry, allowing full flow and thermal analysis of the electrical device. Electromagnetics: STAR-CCM+ has a new solver for Magnetic Vector Potential, which operates in stationary and transient mode and couples to electrical potential solver for electromagnetic problems. Solver can simulate both linear and non-Linear materials. Sample applications: electric motors, alternators, generators, transformers, etc. Liquid Film: the latest version completes the STAR-CCM+ liquid film capability, broadening its applicability and scope. An edge-stripping model automatically removes film and injects droplets when a sharp edge is reached. Energy transport is now possible within a liquid film. Sample applications: vehicle soiling and brake cooling Battery Simulation Module: a pipeline process allows battery set up modifications to be automatically re-executed. STAR-CCM+ v6.06 also allows arbitrary polyhedral meshing for the battery cells and for creating a conformal mesh between posts, tabs, surrounding fluid, mountings, etc. A new sparse solver for electrical solutions is also included. Together these new features provide a significant speedup of solution times. For a complete information and exhaustive list of all new features in STAR-CCM+ v6.06 or to download the latest version today please visit CD-adapco’s user services site or contact your local office.

Geometry Import: new CAD Exchange readers deliver improved reliability and speed when reading native CAD parts and assemblies.

i TRY IT TODAY! www.cd-adapco.com/products/star_ccm_plus

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..::INTRODUCTION Breaking News Follow the latest breaking news online:

www.cd-adapco.com/news

CD-adapco announces the opening of its new Southern California office After years of its office location in Tustin, CD-adapco is pleased to announce the opening of its new SoCal office. Located in Irvine, California, the new, larger facility is specifically designed with customer interaction and future growth in mind. Due to its growth, CD-adapco relocated its Southern California office to a larger space in Irvine at the end of February. The new CD-adapco Irvine office is centrally located between San Diego and Los Angeles. The office space went from a small suite of less than 1,000 square feet in Tustin to a 6,376 square foot office in the Irvine Technology Center. This location provides stateof-the-art computing facilities and dedicated customer areas for training and consultancy technology transfer. In addition, the office features contemporary architecture and attractive landscaping. The Irvine Technology Center is easily accessible by major freeways, I-5 and I-405. Cyndi Taylor, CD-adapco’s Worldwide Facilities Director commented on the move, “The office team is truly happy to have completed the move. We are not using all the space now but we have planned for future growth in the Southern California area.” Taylor continued, “In this move, we increased our fiber optic bandwidth to support larger projects and increase our customer satisfaction of our sales and support teams. We have always worked hard to make visitors to our offices feel welcome. The new office space allows us to do that. We are all looking forward to welcoming new and current customers and associates to join us in the Southern California CD-adapco office.” CD-adapco Los Angeles, 1 Technology Dr. Suite #I825, Irvine, CA 92618-2319 Tel: (+1) 949 398 8330 Fax: (+1) 949 398 8332 Email: info@cd-adapco.com Support: support@cd-adapco.com

CD-adapco announces the opening of its new Detroit office CD-adapco has a new office location in the Detroit, Michigan area. CD-adapco’s Plymouth, Michigan office has recently moved to a new spacious and modern office in Northville, Michigan. The new office is designed with client interaction in mind, with a state-ofthe-art training facility, and dedicated desk space at which customers can work alongside CD-adapco engineers when visiting the office. The new building also includes an expandable data center, allowing CD-adapco to grow its computing resources as quickly as it grows its customer base. The Detroit team is very proud of their new office and they are excited to show it off. The beautiful Northville location is conveniently located just off highway I-275, take the Eight Mile exit and travel west one block to Haggerty Road. CD-adapco is in the “Farmington Hills Corporate Center I” complex at 21800 Haggerty Road, Suite 300 on the 3rd floor. The office phone number has changed to 248-277-4600. CD-adapco is pleased to invite you to visit the new office whenever you are in the Detroit, Michigan area. CD-adapco Detroit, Michigan, 21800 Haggerty Road, Suite 300, Northville, MI 48167 Tel: (+1) 949 398 8330 Fax: (+1) 949 398 8332 Email: info@cd-adapco.com Support: support@cd-adapco.com

i GLOBAL LOCATIONS: www.cd-adapco.com/about/locations

STAR-CD and es-ice v4.16: Latest Version of Simulation Toolkit Released CD-adapco is pleased to announce the release of STAR-CD and es-ice v4.16, the latest version of its comprehensive toolkit for engine simulation. CD-adapco’s purpose is to help customers suceed through the application of engineering simulation: driving innovation in its products AND reducing the time and cost associated with bringing those products to market. STAR-CD increases the potential for innovation through the addition and improvement of physical modeling capabilities, and reduce the time and cost of simulation with the introduction of powerful new automation capabilities. Physical modeling capabilities • Further improvement and new options and capabilities for the G-equation combustion model • New active mode option for DARS-Knock for both ECFM-3Z and G-Equation • Further validation and consolidation of other existing ICE related spray, combustion and emission models. Improved mesh quality Ongoing improvements to trimming, smoothing and prism layer technology leading to better quality meshes and increased solver robustness. Better quality prism layer meshing next to walls. Local mesh refinement for trimmed ICE meshes.

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Automation Ongoing improvements to 2D template generation as well as 2D uniformity and local mesh refinement in strategic areas of the engine to further help ease-ofuse and mesh quality. Automatic valve feature capturing. Mesh replacement and solution mapping for moving mesh ICE applications Further enhanced with more streamlined and clear setup process, making it easier to use and less prone to mistakes. The mesh-to-mesh mapping capability now covers all ICE related combustion and emission capabilities and has also been improved for further mapping accuracy. Improved documentation New Best Practices document to help setup and run ICE simulations. Set of new tutorials covering more advanced multiple cycle and cylinder simulations. Try it out today!

i FOR MORE INFORMATION: www.cd-adapco.com/products/star_cd

..::INTRODUCTION Breaking News

97% of customers would recommend CD-adapco, says survey Conducted during February and March 2011, CD-adapco’s annual customer satisfaction survey elicited a response from 11% of CD-adapco’s 8000 strong user base, including both software and services customers, from across industry and academia.

Panther Racing Demonstrates STAR-CCM+ Simulation Leads to Engineering Success STAR-CCM+ simulation software aided with designing the Panther Racing Team’s IndyCar which JR Hildebrand drove to second place at the Indy 500. CD-adapco would like to congratulate the Panther Racing Team and JR Hildebrand on their second place finish in the Greatest Spectacle in Racing: the Indianapolis 500. Panther Racing uses CD-adapco’s STAR-CCM+ engineering simulation software to optimize the aerodynamic performance and thermal durability of its IndyCar to gain a competitive advantage. Given that Hildebrand was also the fastest rookie in the field, it would appear that the engineers at Panther Racing have capitalized on this advantage. The Panther Racing National Guard IndyCar, piloted by 23-year-old rookie JR Hildebrand, was denied victory in perhaps the most dramatic finale in the 100 year history of the world’s famous motor-race. Retaking the lead late in the race, Hildebrand needed to round the final turn and negotiate traffic to secure his place in racing history. Unfortunately, Hildebrand’s tires lost traction on “marbles” (lumps of discarded tire rubber), losing traction and causing him to crash into the wall of Turn 4 and yield victory to Dan Wheldon. Despite the damage, Hildebrand was able to hang on for another second place finish for Panther Racing making this 4 in a row.

“The disappointment of not winning the race isn’t for me personally, but more for my team, Panther Racing and for everybody in the National Guard,” Hildebrand said. “These guys did an unbelievable job putting us in a position to win the Indianapolis 500 and I don’t think you can say enough about our performance here this month.” CD-adapco’s Senior VP, Bill Clark, was impressed by Hildebrand’s performance on the track but more so by Hildebrand’s attitude immediately following the race: “Our company’s success is heavily dependent on team work and each employee’s desire and commitment to pursue excellence. The poise and humility that Hildebrand exhibited in the moments after the race are a credit to his character and demonstrate his reliance on and respect for his Panther Racing teammates. CD-adapco is proud to have played a small part in this inspirational story. We are confident that Panther Racing will return to the victory lane soon.”

i For more information on panther racing, please visit: www.pantherracing.com

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08 18

..::INTRODUCTION Breaking News Follow the latest breaking news online:

www.cd-adapco.com/news

Olin College Human Powered Vehicle Team Uses STAR-CCM+ and Wins ASME’s East Coast Competition The Olin College Human Powered Vehicle Team recently participated in ASME’s Human Powered Vehicle Competition (East) at the Indianapolis Motor Speedway and with the help of STAR-CCM+, finished first place in all categories. CD-adapco has been a longtime supporter of academia in both teaching and research endeavors. Not only does it offer licenses to academia at dramatically reduced pricing, but it donates STAR-CCM+ to any academic team that can benefit from CAE simulation. Teams have included Formula SAE, Human Powered Submarine, Baja Racing, ecoCAR Challenge, Eco-Marathon and as seen here, Human Powered Vehicle. The team placed first in all categories: first overall, first in design report, first in male sprint (38mph), first in female sprint (30mph) and first in the sprint endurance event. The design of a more aerodynamics shell gave Olin College a great advantage. “We finished first place in all categories and a large part of our success

can be attributed to a well-designed fairing coming from using STAR-CCM+ for analysis,” said Alex Niswander, Team Lead, Olin College. About Olin College Human Powered Vehicle Team The American Society of Mechanical Engineers (ASME) sponsors the Human Powered Vehicle Challenge. Each year, teams from colleges across the nation design, build, and race a vehicle in one of two categories: speed or unrestricted. Olin College has participated in the speed class since 2007. Speed class vehicles are typically fully faired bicycles, and are judged based on a technical design report, a sprint competition, and an endurance competition. In its short history, Olin has had a very successful showing at competition. This past year Olin swept the speed class taking 1st in every event.

i MORE INFORMATION: hpv.olin.edu/

Best pape r/presentation award for PACE Formula 1 car CFD project A team of mechanical engineering students from Brigham Young University won the Best Paper/Presentation Award at the PACE Forum hosted by the University of British Columbia in Vancouver, British Columbia, Canada, July 27-29, 2011. Led by Professors Greg Jensen and Steven Gorrell, Satyan Chandra and Allison Lee worked on the project. As part of the PACE program, the Formula 1 car was developed in a collaborative effort between 26 different universities in 10 countries. Several companies, including GM, Siemens and HP were also part of the consortium. This project focused on using Computational Fluid Dynamics (CFD) to understand how the Formula 1 car would behave during high speed maneuvers, in order to ensure stability at speeds exceeding 200 miles per hour. “There is nothing that has wowed me more than cars and airplanes,” commented Chandra. “I love cars, and am very passionate about Automotive Engineering. I taught myself to drive in the 4th grade, and have a professional racing license. Naturally, this project was very appealing to me!” Chandra, originally from India, worked with Allison Lee, a senior from Mesa, AZ, to learn how to use STAR-CCM+, perform the simulations and analysis, write the paper, and organize the presentation. “It was a comprehensive research and development effort,” said Chandra. “The focus was first to obtain accurate and highly representative aerodynamic representations of the car, optimize the design of the front and rear wings, and then work on the presentation and the paper for the conference and hopefully later publication.” The research also involved working with engineers from CD-adapco.

i MORE INFORMATION: me.byu.edu/

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The project came away from the PACE Forum with the Best Paper/Presentation award. Dr. Jensen presented the paper, which was an analytical study on air flow effects and resulting dynamics on the PACE Formula 1 race car. The study incorporated Computational Fluid Dynamic (CFD) analysis and simulation to maximize down force and minimize drag during high speed maneuvers of the race car. Using STAR-CCM+ and mentoring provided by Dr. Lorenzo Crosatti, application engineer from CD-adapco, the simulation employed efficient meshing techniques and realistic loading conditions in order to understand down force on front and rear wing portions of the car as well as drag created by all exterior surfaces. The study also ensured safety of operation and allowed for optimization of performance for racing conditions. “This particular CFD project spanned eight months and included students, professors, and industry representatives,” stated Chandra. “We spent lots of late nights, with lots of troubleshooting and overcoming difficulties. It was truly a challenge with the sheer complexity of it. But there was nothing I would have rather done.”

For more information: info@cd-adapco.com Follow us online. www.cd-adapco.com/products/STAR-CCM_plus

Engineering simulation for a full range of environmental conditions

STAR-CCM+: POWER with ease Optimal Thermal Management in Electronic Systems Design Delivering the power of integrated fluid dynamics & heat transfer simulation technology with the ease of modeling real & complex geometries

See first hand how Raytheon is tackling thermal management problems using STAR-CCM+ On-Demand Recording Now Available: www.cd-adapco.com/ec01

..::FEATURE ARTICLE Batteries

❐ TRIVIA

Timeline of Battery History 1748

“Battery” American statesman and inventor, Benjamin Franklin coined the term “battery” when he used it to describe an array of Leyden jars by analogy to an artillery battery.

1800

Voltaic Pile Italian scientist, Alessandro Volta discovered the first practical method of generating electricity and invented the Voltaic Pile, the first “wet cell battery” that produced a reliable, steady current of electricity.

1836

Daniell Cell Englishman, John F. Daniell invented the Daniell Cell, an improved version of the Volta cell, which was used in homes for over 100 years to power objects such as telegraphs, telephones, and doorbells.

1839

Fuel Cell Welsh judge and physical scientist, William Robert Grove developed the first fuel cell.

1859

Rechargeable French inventor, Gaston Plante developed the first practical storage lead-acid battery that could be recharged. This type of battery is primarily used in cars today.

1866

Dry Cell French engineer, Georges Leclanché developed a transportable carbon-zinc dry cell, also called the Leclanché cell.

1901

Alkaline Storage American inventor, Thomas Edison invented the alkaline storage battery.

1954

Solar Cells Americam researchers, Gerald Pearson, Calvin Fuller and Daryl Chapin invented the first solar battery.

1985

Lithium-ion Battery Japanese chemist, Akira Yoshino invented the Li-ion battery under its current form. It was subsequently commercialized in 1991 by Sony and Asahi Kasei.

ABOVE Battery pack modeled in STAR-CCM+

A New, Groundbreaking Tool to Simulate Batteries Interview with Steve Hartridge, Director, Electric & Hybrid Vehicles on CD-adapco’s unique simulation tool for the design and analysis of Li-ion batteries

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..::FEATURE ARTICLE Batteries

One year after the STAR-CCM+ Battery Simulation Module (BSM) was first released, we meet with Steve Hartridge, Director, Electric & Hybrid Vehicles at CD-adapco, for an update on this unique battery technology. Could you please describe the product in a few words Of course. In collaboration with Battery Design LLC, we have developed a unique working methodology for the analysis of electrochemical and thermal performance of lithium-ion battery cells, modules and pack installations. Who is this product intended for? As you can imagine, more or less every major player in the automotive industry is interested in the electrification of the powertrain and related issues. They are aware of the value of numeric functional assurance and of CFD simulation methods. In the field of electric vehicles, new application areas are opening up. For example, the positioning of the battery in the vehicle must be studied in detail to avoid the negative impact of a poorly installed battery pack. In addition, companies that previously have not been concerned with simulation, such as battery manufacturers, have now entered the arena. For that fact alone, we are dealing with a growing market. What specific expertise does CD-adapco contribute? What do the cooperation partners provide? An important collaboration is with Battery Design LLC, about which an announcement was made in November 2009. The company, based in California, has over ten years of experience with the development of lithiumion battery analysis software and cell design consulting. Together, we provide users with a complete simulation process, from the definition of the battery cell prototype or new active coatings to the visualization of their electrochemical and thermal performance as part of a large traction battery pack. We also work with a number of major players in the battery industry and research institutions, such as the ASCS (Automotive Simulation Center Stuttgart) and the US National Renewable Energy Laboratory. Hereby, processes developed as part of the ongoing cooperation between CD-adapco and Battery Design LLC are used and validated in very rigorous situations, thereby ensuring that our methodology and solutions remain state-of-the-art. You stated this product is unique. What is unique about it? The detail of the underlying electrochemistry models and the battery cell understanding: having the ability to compute both the thermal and the electrical/ electrochemical solution within one code and ensure that all phenomena are included to achieve the correct overall performance. Could you describe the process? This new battery technology allows the user to migrate from short length scale simulations, such as studies of a detailed single cell, to complex battery modules, packs or complete installations, including hundreds of battery cells and their surrounding structure and cooling system. The same battery performance model, currently a range of three, can be used in any of the different length scale models. This removes the need for duplicating or simplifying the engineering tasks, thereby facilitating the division of labor. One engineer, probably part of the cell team, creates a battery cell model and begins running cell level simulations. This model can then be passed on to another analyst, maybe working in the application team, who uses it to create complex simulations of battery modules or packs. This process ensures that there is no duplication in the two engineersâ&#x20AC;&#x2122; time while providing a high fidelity numerical model and coupled flow, thermal & electrochemical solution. Do such analyses need much CPU time? That depends. Obviously certain details required for the exact modeling of batteries mean overhead and this is reflected in extended computing time. Of course, it is also true that CFD and conventional calculation methods, such as the finite-volume method, already demand maximum computing resources. Some of the battery models we have implemented boast a high performance even on simple desktop workstations: running through the entire process requires only a few minutes. However, the computing time is very dependent on the geometry details and the desired quality of the calculation results.

Does the grid generation required by such a task pose a particular challenge? STAR-CCM+ is a CFD code for a wide range of applications, and as such includes many state-of-the-art meshing tools. Due to the layout, batteries consist of recurring identical structures; cells that typically occur between 30 and 100 times. For this, very thin elements are sometimes used in the form of plates. All these can be easily interlinked with the meshing methods implemented in STAR-CCM+. I would also like to add that independent thermal and electrochemical resolutions can be used. Typically, this allows the user to get a higher accuracy of the flow/ thermal results while optimizing the speed of the electrochemical solution. Are you saying the geometries do not require particular attention? The geometry may well be complex, but we can handle them and have no need to develop special algorithms or adapt existing ones. Besides, not only can flat battery cells be simulated, but the analysis method has been extended to spiral cells, such as cylindrical and prismatic mandrel wound cell jellyrolls. What can you tell us about the roadmap for this application? We are moving into the field of electrochemical reaction mechanisms. We have a clearly defined range of functions with a fixed timetable that we want to make available to our customers. Recently, a 3D electrochemistry solver has been created for microscale analyses. This development extends the applicable length scales of battery simulation to unit cell on a microstructural level. The method removes the macro-homogeneous elements with 1D or pseudo 2D electrochemistry models and chooses instead to represent the various phases within the electrodes as distinct regions: active material, electrolyte, conductivity aid, separator and collector. The geometry is now resolved, and the simplified fundamental equations have been added to STAR-CCM+â&#x20AC;&#x2122; solver capabilities, thereby enabling the computation of the following quantities: - salt concentration in the electrolyte region; - lithium concentration in the positive and negative active materials; - potential in both the solid and electrolyte regions; - thermal energy within all of the regions. Using this technology, cell designers and material specialists can explore and optimize active material packing ratio, particle shape and size distribution, electrolyte properties and other aspects under various charge and discharge conditions. This is a bold development which CD-adapco is first to bring to market and extends the length scale range to which simulation technology can be applied in this field. Not everybody is able to operate a CFD code. Will your company support its customers by providing computing services? Certainly! It is not our strategy to develop a certain functionality in secrecy and to offer it on the next day via our code to our customers. We develop technology in close collaboration with our customers as part of engineering services. The underlying logic is quite clear: the more we work together with customers and their internal and external clients, the more developments and technology we can implement in later releases, which, in turn, can be made available to a wider userbase. <

ABOVE Screen representation of the pack within the STAR-CCM+ interface

i access articles, brochures, flyers, magazines, webinar recordings & more: www.cd-adapco.com/downloads

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..::FEATUREâ&#x20AC;&#x2C6;ARTICLE Electric Machines

STAR-CCM+ Breaks New Ground With Electromagnetic Capabilities Stephen Ferguson - CD-adapco

CD-adapco Releases SPEED In June 2011, CD-adapco acquired the electric machine software, SPEED. The version 2011 release is available with over 350 enhancements. SPEED software allows users to design electric machines such as induction motors (polyphase/1phase); brushless permanent-magnet motors (square wave/sine wave); d.c. brush motors; switched reluctance motors; and synchronous reluctance motors. Many of the new features in SPEED are intended for generators as well. With over 1500 customers using SPEED for over 20 years, they are among the leading manufacturers, designers, developers and users of electric machines.

â?? FACT

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..::FEATUREâ&#x20AC;&#x2C6;ARTICLE Electric Machines

The automotive industry is seeing a dramatic shift towards fuel efficient vehicles. This allows consumers to reduce their personal greenhouse gas emissions and gives them the opportunity to use alternatively powered transportation. This trend is leading to the increasing electrification of vehicles from mild hybrids (storing braking energy in a device), to strong serial hybrids (where the electric motor is permanently connected to the axles), to full electric vehicles (where the only driving force is the electric motor). In all these â&#x20AC;&#x153;hybridâ&#x20AC;? vehicles, there is the need for a significant electric machine which was not part of the mechanical design or cost structure of previous, older products. As the automotive industry reacts to changing consumer demands, driven in some part by the incentives available from certain governments, they turn to their partners and established suppliers to help find solutions. With this clear need in mind, CD-adapco, established as the No. 1 independent simulation provider to the automotive industry, has begun a significant development effort to enhance its class-leading simulation tool, STAR-CCM+, to cope with these new demands. The challenge is to provide a process which is easy to use but also powerful enough to capture all the physical phenomena present in an electric motor. The design and simulation problem is made all the more acute as auto manufacturers push components to the edge of their operating envelope in order to outperform each other. To be able to simulate such extreme conditions, a software tool must capture all the relevant physics within one numerical solution and compute results for all mechanisms during this single solution. This objective drives the enhancement of STAR-CCM+ to an ever wider audience, capturing an ever increasing physical spectrum. g

ABOVE Electric Machines can now be simulated with STAR-CCM+

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..::FEATURE ARTICLE Electric Machines

ABOVE Axial Flux Machine Simulation

For more information about Electric Machines, please visit:

www.cd-adapco.com In electric motor development, multiple engineers working in different disciplines typically handle the coupled problem of electromagnetically generated thermal analysis. For example, while engineers with electromagnetic backgrounds evaluate the motor performance, the reliability is assessed by a different set of engineers who use a combination of mechanical and thermal tools. It is often quoted that a sustained 10°C increase in operating temperature will reduce the insulation life within a motor by 50%. This shows the value of even small incremental improvements in a motor design. Moreover, a 50°C increase in winding temperature can increase the electrical resistance by 20% and therefore lead to a significant increase in the I2R losses of the system. These engineering ‘rules of thumb’ help explain why motor design companies invest heavily in simulation. Indeed, deploying simulation in the early stages of the design process ensures correct solutions are chosen, avoiding expensive redesigns as the motor nears production.

ABOVE Axial Flux Machine: Magnetic Vector Potential

To address this need, CD-adapco is developing electromagnetic capabilities in STAR-CCM+. This capability, when coupled with the existing models - namely fluid flow, heat transfer and structural mechanics - will enable the electromechanical, thermal and structural analyses to be carried out from the same model. This will allow simulation engineers to accurately visualize the performance of electric machines at the edge of their operating envelopes. One example of this coupled behavior is as the temperatures of the permanent magnets within the electric machine increase during use, their magnetic properties change and affect the output of the motor. To maintain the power output, an increase in input current is needed, which in turn leads to a further increase in the magnets temperatures If this continues, the magnets can be permanently damaged, leading to a loss in performance of the electric machine. Due to this temperature dependence, engineers typically design permanent magnet motors with a specific magnet temperature threshold in mind. Magnets that can operate at higher thresholds

ABOVE Various Electric Machines Simulations

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..::FEATURE ARTICLE Electric Machines

ABOVE Using SPEED as a design tool

are more costly, and strongly impact the overall cost of the design. In order to deliver the highest performance at the lowest cost, engineers must carefully evaluate the magnets operating temperatures. Once a motor design has been established, STAR-CCM+ can be used to predict the effects of the installation on the motor performance, and assess the detailed design of the cooling system, whether it uses forced air cooling, liquid cooling or simply natural convection of air from the surface of the motor. Furthermore, if radiation effects are significant, these too can be included in the simulation. Besides electric motors, there is a whole host of applications, such as induction heaters, eddy current braking systems and linear actuators, that require an electromagnetic solution to properly predict heat transfer. STAR-CCM+’ new capability will be able to simulate such devices. Development in CD-adapco’s EMAG code continues at a frenetic pace and this enhancement of the tool will be available, in its initial form, to consumers later this year.<

i For more information, please speak to your CD-adapco representative or visit: www.cd-adapco.com

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..::FEATURE ARTICLE Electric Machines For more information about Electric Machines, please visit:

www.cd-adapco.com

Rise of the (Electric) Machines: CD-adapco & the Need for SPEED Scott Del Porte - CD-adapco

CD-adapco recently finalized the purchase of SPEED, a leading electric machines design software tool developed at the University of Glasgow. SPEED software, which has been in development for the last 25 years, comprises a client base of over 1000 engineers, including many of the world’s leading manufacturers, designers, developers and users of electric machines. SPEED allows users to design electric machines such as induction motors (polyphase/1-phase), brushless permanent-magnet motors (square wave/sine wave), d.c. brush motors, switched reluctance motors, and synchronous reluctance motors. Many of the new features in SPEED are intended for generators as well. Professor Tim Miller, Originator and Director of the SPEED software labs said, “After 25 years in the University of Glasgow, I am delighted that SPEED is joining CD-adapco. It is a perfectly natural transition from one of the oldest UK universities, with one of the longest and richest histories of academic/industrial interaction in engineering. The combination of SPEED and CD-adapco lays the foundation for a new phase of development in software engineering services to manufacturing companies in electric machinery, covering all sectors including exciting new developments in power generation and electric/hybrid vehicles, as well as all our varied fields of activity.” He continued, “I am personally looking forward to a renewal of all aspects of SPEED’s service to this vital group of industries, balancing the need for continuity with the need for development and integration with related design tools from CDadapco themselves and others with whom we have worked for many years. The philosophy of customer service through the provision of leading enabling design tools is identical in SPEED and CD-adapco, so I believe we will see a vigorous and stimulating new era. I am very proud to be part of it and I hope all our customers will stay with us to realize the full potential of our partnership.” Professor John Marsh, Head of the School of Engineering at the University of Glasgow and instrumental in the deal, added, “This is a great example of how knowledge developed within the university can create a product which will have significant value for users in this field. We are very proud of SPEED’s heritage and

the position it holds in the marketplace and are pleased to work with CD-adapco to allow it to flourish.” CD-adapco’s President, Steve MacDonald explained, “SPEED software takes CD-adapco to the forefront of the electric machine design and is absolutely complementary to the ongoing organic developments in-house: specifically, to create a detailed 3D electromagnetic solver which will become part of STAR-CCM+ and move the market forward for electric machine simulation.” MacDonald went on to comment, “These developments mark a significant commitment from CD-adapco in the electromagnetic field, the ultimate aim to further strengthen our simulation tool and provide more solutions to our customers. For us to be a serious player in this area requires expertise and one of the most renowned people walking on this planet in the area of electric motors is Professor Tim Miller. We are delighted to have joined forces with him.” <

Delivering on their promise to accelerate the development of the SPEED product, the first CD-adapco branded release of SPEED contains over 350 enhancements. Dr. Tim Miller, originator of SPEED and now a consultant to CD-adapco commented, “While this is a great development for SPEED and all our customers, we’re wasting no time in making a complete new release of all the SPEED software and its documentation. One compelling reason why we’ve joined forces with CD-adapco is to make SPEED even better.” Miller continued, “An early sign of SPEED’s progress is the intense collaboration now underway, to share geometry and other design parameters with STAR-CCM+. Another is the development of a 3D electromagnetic solver in STAR-CCM+. And a third is the intense training activity that SPEED is running — two or three times the previous level.”

i MORE ABOUT ELECTRIC MACHINES: www.cd-adapco.com

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..::FEATURE ARTICLE Electric Machines

The industry highlights of SPEED’s new features are: Automotive (Hybrid & Electric Vehicles as well as Commercial, Industrial, Agricultural & Mining Special Vehicles) SPEED’s finite-element GoFER and embedded solver combine comprehensive analytical models covering all aspects of the design of these machines, including thermal, electromagnetic and drive control. Enhancements have been made in all aspects of the design calculations to improve accuracy and cover an even wider range of machine geometries. Of particular importance is the efficient utilization, and elimination, of magnets. The SPEED suite of programs is now structured to give seamless design capability over the entire range of permanent-magnet machines and the alternatives including hybrid combinations. SPEED covers the entire range of power, voltage, and speed used in vehicle systems. SPEED plays a key role not only in drivetrain engineering but also in auxiliaries such as starter-generators, many kinds of pumps, blowers, actuators, and even the KERS systems used in F1. Refrigeration, Domestic Appliances & Water Efficiency requirements are driving these industries towards continual technological evolution, in a context of extreme cost pressure and material supply issues. SPEED is used as the main design tool in several leading companies manufacturing compressors, washing-machine drive motors, pumps and fans worldwide. The technology covers induction motors (both 1-phase and 3-phase), permanent-magnet brushless motors, and line-start PM motors. Switched reluctance motors are also used in a few key applications. SPEED’s ability to characterize products and not just concepts is one its main assets in serving this sector. Improvements have been made in all programs in relation to machine geometry, loss calculations, drive control, and finite-element analysis. Aerospace High power-density, high speed and fault tolerance are key requirements in aerospace. SPEED has been used for many applications including actuators, pumps, and starter-generators, and we are “on” some of the most advanced electrically-equipped aircraft. Brushless PM machines and switched reluctance machines are the main technologies. In both of these areas, SPEED has new features improving the range of machine geometry, and the calculation of electromagnetic and thermal performance. Industrial SPEED is behind the design of some of the world’s most efficient AC variablespeed drives, using brushless SPM and IPM motor configurations. The code is use not only in high-efficiency industrial drives, but also in precision servomotor systems. We’ve made special efforts to extend SPEED into generators, with a new embedded finite-element solver to cope with a wide variety of load specifications, and automatic calculation of generator characteristics for woundfield synchronous generators. We’ve added the doubly-fed induction machine to the range. Improvements in machine geometry, finite-element analysis, drive control, and thermal modeling have been achieved. SPEED’s technology covers all kinds of brushless PM machines, synchronous and switched reluctance machines, induction machines and DC machines. Axial-flux machines can also be calculated using a new addition to the SPEED system.

While this is a great development for SPEED and all our customers, we’re wasting no time in making a complete new release of all the SPEED software and its documentation. One compelling reason why we’ve joined forces with CD-adapco is to make SPEED even better.

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..::FEATUREâ&#x20AC;&#x2C6;ARTICLE Electronics

Pushing the Boundaries of Electronics Design Stephen Ferguson - CD-adapco

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..::FEATURE ARTICLE Electronics

One solution to these problems is the STAR-CCM+ surface wrapper: a tool that creates a geometric representation by shrink-wrapping a high-resolution surface on the complex aspects of the geometry. It allows the user to ignore many of the inadequacies of the 3D model and create a geometric representation that is ready for simulation.

The control of component and system temperatures remains one the most significant challenges in the design of electronic systems. From chip to chassis and beyond, excessive thermal loading limits the maximum performance of an electronic device and significantly increases the energy footprint of the system. Whereas previous generations of engineers were able to rely on a combination of engineering intuition and experience to design the cooling of their electronic systems, the ever-increasing, consumer-led demand for greater performance in a smaller package, means this type of speculative prototyping is no-longer effective. Reliance on intuition to predict the cooling of complex systems is an almost certain guarantee of bad results. Not only is trial-and-error prototyping ill suited for today’s demanding markets, it also fails to derive the full value of design processes. The time and cost associated with this approach limits an engineering organization’s opportunity to optimize designs, by limiting the resources available to explore all the ideas designers may have. This affects products by decreasing profit margins, delaying product time to market, and increasing product cost. Perhaps most importantly, it limits the innovation that can be designed into the product itself. The simple truth is that, in an increasingly competitive market place, only simulation can provide the necessary insight into the performance of a new device: “If I do not use simulation and the physical test does not give me the right information the first time, I don’t know how to correct that situation,” said Andrew Slater, Director of Flight Sciences at Gulfstream Aerospace Corp. “If I have to fix it, I am very constrained, or I’m into a very expensive project to figure out how to fix it. The benefit of having simulation is that I get an indication of how to change the environment and fix the particular problem.” Applications Electronics simulation can take place on many levels; two of the most important are at the component level and the system level. Components, such as dies and heat spreaders, are made of a wide assortment of materials, from ceramics and silicon to metal and hybrid materials. Each material reacts differently to changes in temperature, expanding and contracting at disparate rates. The interactions

among the different materials can be critical. If you have a component made of conflicting materials, where one material’s volume grows significantly as it expands with heat and the other’s changes little, the component can fail as a result of the conflict. At the component level, therefore, design engineers must understand the thermal expansion and thermal stress characteristics of the materials making up the parts they use. At the system level, design engineers pay some attention to structural considerations, but in thermal management, these concerns tend to take a backseat to the prediction of the likely flow path. By directing a stream of air past heat generating components or sensitive components, convection can be used to directly remove thermal energy from the enclosure. Maintaining a thermal environment that allows the components to remain in a safe temperature operating range is the dominant focus. The analysis at this level usually does not consider all possible conditions. Instead, attention is focused on worst-case scenarios. “We don’t look at all possible scenarios,” said Gary Schwartz, Engineering Fellow at Raytheon Network Centric Systems. “We just look at the worst scenario. If the electronics can survive that, they can survive mundane conditions.” Unfortunately, the difficulties encountered in electronics design are ramping up as systems, interactions, and operating factors become increasingly complex. “Previously, we would have looked at individual parts, by themselves,” says Schwartz. “Individually, the parts may be all right, but the interaction of all the parts may not. The key now is to look at how all the parts work together.” This situation is exacerbated by the fact that modern electronic systems need to be designed to strict energy usage guidelines. This means that engineers can also no longer rely on the “brute-force” approach of flooding an electronics package with the largest possible amount of cold air. Again, where a more subtle approach is required, the insight gained through simulation is key in determining an energy efficient, yet effective cooling system. g

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..::FEATURE ARTICLE Electronics

Visit the link below for our ELECTRONICS SPECIAL REPORT:

www.cd-adapco.com/downloads/special_reports ABOVE Flow streamlines and temperature profile under extreme conditions inside a power supply

Challenges The traditional physics involved in the simulation of electronic systems, such as heat conduction and convection, are well understood. On paper, many simulation tools have the ability to solve problems involving these physics. However, solving industrial strength problems, within the constraints of a product development program, is often much tougher in reality than it seems on paper. Today, many traditional simulation tools struggle to keep up with the fast-paced development schedules that engineering teams are confronted with. In a world where customers need to know performance characteristics in order to keep development moving forward, simulation has some inherent inefficiencies that are keeping design teams from delivering their results quickly enough to have the maximum impact on a program. The inefficiencies are in two main areas: the simulation process itself and the limited number of physical environments that can be represented virtually. One of the biggest stumbling blocks is geometry creation and geometry capture. The Starting Point Geometry is the starting point of any simulation. It is the virtual representation of a system and its components. The geometry typically comes from CAD tools, in either a 2D or 3D format. CAD geometry may come in a simplified, conceptual form, quickly created without adequate attention to errors or, more likely, is overly detailed, containing more definition than the simulation requires. Both production geometry and simplified geometry can contain a lot of errors and problems that must be addressed before the geometry can efficiently be used as a basis for an engineering simulation. Usually, a design engineer creates the geometry. There are times, however, where no CAD data exists, which forces the

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simulation engineer to create it directly within the simulation tool. “The most difficult part of the process is dealing with geometrically complex parts—taking those parts from a design model, such as Pro/Engineer or NX, and putting them into some kind of simulation code so that you can use that geometry,” said Raytheon’s Schwartz. “There is potentially a lot of clean-up that has to be done. Sometimes you have to massage the geometry of the parts to create a model.” Using the wrong simulation tool, engineers are forced to spend weeks attempting to make the geometry simulation-ready. They have to de-feature it, remodel or completely remove aspects, destroying in the process the link to the original CAD model. This reduces the impact that simulation can have on product development because the time required to create the geometry and prepare it for simulation is sometimes longer that it would take an engineer to prototype and test a configuration. “There are times when it may take hours or days just to work on one part to get it to the point where you can actually include it in your simulation,” said Schwartz. “That is the bottleneck. Time is a real factor. You don’t want to spend three months building a model because by that point it’s of no relevance. You need to do things fairly rapidly to have an impact on the design.” The Fix One solution to these problems is the STAR-CCM+ surface wrapper: a tool that creates a geometric representation by shrink-wrapping a high-resolution surface on the complex aspects of the geometry. It allows the user to ignore many of the inadequacies of the 3D model and create a geometric representation that is ready for simulation.

..::FEATURE ARTICLE Electronics

For those involved in electronics design, the most common use of the surface wrapper is for the enclosures that house large numbers of components. The surface wrapper creates one solid surface over these areas. If the enclosure is made of sheet metal, the surface wrapper can quickly help the user address the gaps inherent due to bend reliefs, assembly tolerances, and overlapping tabs. If the enclosure is made of molded parts, the complex geometry of the parts themselves as well as the interlocking connection between parts can be quickly prepped for analysis by the surface wrapper. The corners of enclosures often have gaps that present significant problems. “The designer may have built a rack in CATIA that shows gaps around the shelves for manufacturing tolerance,” said Gulfstream’s Slater. “The gaps become flow paths that in reality should not be there, and they won’t close the boundary properly from a modeling perspective.” One of the surface wrapper’s settings, called gap closure, lets you specify the size of the holes in the assembly that are closed automatically. Another setting called contact prevention, allows the simulation engineer to maintain spacing between components that should not come in contact with each other. With the surface wrapper, you can control the replica’s resolution either globally or on the part, surface, and edge level and automatically take care of problematic areas. The surface wrapper not only provides a way of transforming bad or difficult geometry into a form ready for efficient simulation; it also helps to dramatically shorten what has been a cumbersome and time-consuming process that prevented designers from being more productive and reaping the full benefits of simulation. “The speed of being able to put these models together and start using them is quite important,” said Slater. “The power with which we can handle the geometries and meshing within the simulation code is quite important.” Once a high quality closed surface is available, STAR-CCM+ can automatically fill the enclosure with a computational mesh of trimmed hexahedral or polyhedral cells, allowing the simulation to proceed. New Problems, Broader Horizons Until recently, electronics designers have been fully occupied with the solution of traditional problems, such as conduction and convection. However, advances in simulation technology (such as those described above) are freeing designers to tackle more unusual problems such as contamination resistance, water intrusion, and condensation. For example, military electronic systems need to be able to operate in the desert, where sand ingression is a challenge. Portable electronic devices such as cell phones are increasingly required to withstand water intrusion. Even cooling problems are now increasingly relying upon “non-standard technology”. To meet the increased cooling requirements of the latest generation of electronic equipment, engineers are expanding from simple air and gas cooling

systems to liquid and spray cooling approaches. To develop these new systems, they must use heat exchanger models that allow them to interact with multiple fluids and spray cooling, as well as represent multiphase environments where liquid droplets interact with air, and evaporation and condensation come into play. The problem is that many mainstream simulation tools capable of solving simple conduction and convection problems cannot accurately represent the physics required to simulate these scenarios virtually. As a full-spectrum simulation tool that is used to solve fluid and structural mechanics problems over a wide range of industries, STAR-CCM+ is uniquely able to address the most difficult physics problems that electronics engineers encounter. This gives them the confidence to develop and optimize cooling technologies for this new class of electronics problems, limited only by what is physically possible, and not by shortcomings of their simulation tool. Benefits of Best-in-Class Simulation When you look at the bottom line of the balance sheet, the question isn’t whether you should use simulation to design electronic systems. Simulation enables you to visualize what is happening in the component or system you are designing and why. It allows you to make informed design decisions, optimize product performance, manage risks, and pursue innovation. “Once you start to use simulation and you build your confidence with it, you can push the boundaries of your design and make sure that you achieve the maximum value of the product,” said Gulfstream’s Slater. “After we see the simulation results, the light bulb goes on,” said Raytheon’s Schwartz. “Until we do the simulation, it’s difficult to know what’s really going to be the behavior or response. We are just guessing unless we do some kind of simulation because things have gotten so complex that you really don’t know what the behavior is going to be like until you build the model, run the simulation, and look at the results. It shows us what we have to change to get what we want.” The real question is what features you should require in the simulation tool that you use. Find the tool that includes the most efficient surface wrapper, and the process of converting CAD data into a simulation-ready geometry is no longer prohibitive in terms of time and resources. Complex surfaces do not preclude accurate representation. Select the software that offers advanced meshing, and no project is too big. With the right mesh, you can get the optimum benefit from your computing resources. Choose the simulation tool that has the greatest variety of physics models, and you can design the new class of electronics that have captured the market’s attention. Also make sure that you choose the simulation tool that provides the best support organization to allow you to most effectively leverage the software in the design cycle. <

ABOVE Simulation results showing flow through a cooling fan and temperature profile on a heat sink inside an electronics enclosure

i ORDER OR DOWNLOAD OUR ELECTRONICS SPECIAL REPORT: www.cd-adapco.com/industries/electronics

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..::FEATUREâ&#x20AC;&#x2C6;ARTICLE Electronics

BELOW Trimmed mesh and pressure distribution

Read about how our software is used in the Electronics industry:

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Is your Electronics Cooling Software Stephen Ferguson - CD-adapco

For electronic devices, temperature is a limiting factor. Packing technology, driven by constant consumer demand and competitive pressure, allows higher power density than current cooling technology can handle. Sustained elevated temperatures act to not only reduce component efficiency, but also to reduce product life. Effectively controlling the temperature of electronic systems, in an intelligent and sustainable manner, is therefore the key to producing smaller, more powerful and more resilient electronic devices.

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..::FEATURE ARTICLE Electronics

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STAR-CCM+ STAR-CCM+ is designed to handle complex problems and large model sizes. It has been used by our industrial partners for calculations numbering billions of computational cells far beyond the size of any electronics-cooling problem. No matter how big, or how complex your design scenario is, STAR-CCM+ allows you to solve it without compromise, using a model size that fits your problem and ultimately utilizes less assumption. Below - Team Lotus Renault CFD Center: a $50M underground bunker for computers

Air-cooling, while effective for low- to medium-power applications (where space and noise are not a concern), is generally neither practical nor cost-effective for high-powered systems. Put simply, the “brute force” approach, in which high-temperature components are strapped onto a large aluminum heat sink and blasted with cold air is no longer an option. So, what is the best method for cooling high-power electronics when air solutions are not practical or possible? The future of electronics cooling involves the implementation of cooling strategies that leverage multiple modes of heat transfer. The problem for engineers developing electronics cooling solutions is that many of the simulation tools were developed entirely for analyzing simple “bread-and-butter” scenarios. These tools, although adequate for obtaining a “quick and dirty” fan-assisted air-cooled solutions, are generally not fit for simulating the more advanced physics required to represent more recent and sophisticated cooling strategies. In this article, we look at some of the problems that simulation software will have to face in the electronics industry, and ask the question: “Is your electronics cooling software fit for purpose?” A Question of Scale The length scales represented in electronics cooling problems can span 11 orders of magnitude: from individual transistors that are measured in nanometers (of order 10-9 m) to entire datacenters (of order 102 m). Now obviously, no tool can account for every single electronic component in a datacenter cooling simulation. Even if it were possible to do so, it is doubtful that such a simulation would provide additional useful information. Out of necessity, engineers use a combination of simplifying assumptions and imposed boundary conditions to focus the simulation on those length scales that are most important for the simulation (using generous amounts of “engineering judgment” in the process). However, care must be taken not to over simplify things: if the assumptions are too great, or the imposed boundary conditions are too unrepresentative, then the results predicted by the simulation begin to diverge from those that would occur in reality. When this happens, no amount of judgment (engineering or otherwise) can rescue useful data from the simulation. Worse still, wrong or inaccurate results can mislead the design process, potentially sending the product up a non-optimal design branch. So, ideally your simulation tool will allow you to solve problems across multiple length scales. Instead of just simulating flow across a single circuit board, you want to be able to model a whole blade server, or better still, how several blade servers interact with each other and their environment. Natural Convection and Thermal Radiation In traditional forced convection “air-cooled” systems, thermal radiation plays a relatively minor role in the overall heat transfer, typically accounting for less than 5% of the thermal energy rejected by the system (with the rest split evenly between convection and conduction). However, in “no flow” situations, whether by design or in unintentionally “dead” regions of the compartment, radiation plays a much more important role accounting for between 30-50% of heat transfer. Simply neglected in many simulations, for the reasons described below, including radiation heat transfer in a simulation will generally act to decrease maximum temperature in the system, spread out the temperature distribution and reduce the exterior surface temperature (touch temperature). g

Multi-Core Processing ❐ FACT

STAR-CCM+ includes parallel view factor calculation, which allows users to exploit the processing power of multiple computer cores when performing radiation view factor calculations.

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..::FEATUREâ&#x20AC;&#x2C6;ARTICLE Electronics

The All-in-One Muti-Physics Toolbox More than just a CFD code, STAR-CCM+ is a complete multi-physics toolbox, able to solve flow, thermal and stress problems involving multiple phases. From liquid jets to water ingression, STAR-CCM+ allows you to simulate any cooling strategy that you can define, and even the effect of what happens when those strategies go wrong.

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..::FEATURE ARTICLE Electronics

However, including radiation heat transfer can significantly increase the computational overhead for a simulation, as view factors (basically lines of sight) must be calculated for every computational face of every component in the system. Although these view factors need only be calculated once per geometry, this process can be computationally expensive even for a large uncluttered enclosure. In a typical crowded electronics enclosure, consisting of hundreds, if not thousands of components, calculating these view factors is beyond the capability of a single processor machine (both in terms of memory requirement and physical time needed to complete the calculation). By including radiation, you can reveal the effects of an additional heat flow path – this is critical in low flow or no flow situations and can be important when trying to squeeze every degree of cooling from a forced convection system. Liquid Cooling: Chilling, Dunking and Spraying While air-cooling continues to be the most widely employed method of thermal management, its ultimate effectiveness is always limited by the fact that air has relatively poor thermal capacity compared to other fluids. For serious cooling impact for high-power density systems, designers are increasingly turning to different types of liquid cooling. A common feature of liquid-based cooling systems is that they exploit the additional heat transfer of phase change to increase the cooling effect of the liquid. Because of the higher thermal capacity of the coolant liquid, they benefit from greater sensible heat transfer (which raises the temperature of the coolant) and latent heat transfer (which changes the phase of the coolant, through boiling or evaporation). The simplest way of doing this is by “indirect” liquid cooling, where the coolant never comes into direct contact with the electronic component being cooled, usually accomplished through the attachment of a liquid cooled “cold plate” which is attached to the chip. A more effective (although less practical) solution is to submerge the chip directly into a (non electrically conductive) coolant. If the temperature of the component increases beyond a critical level (the boiling point of the liquid), then nucleate boiling will commence, greatly increasing the heat flux from the chip to the fluid. At high temperature, this approach is around 5 times more effective than indirect liquid cooling, and about 25 times more effective than direct air-cooling. However, this approach makes routine maintenance much more difficult (as the components must be removed from the liquid bath and cleaned prior to inspection). Care must be taken so that the boiling regime does not progress to “film boiling” at which point the component becomes surrounded by a film of vapor, and heat transfer is suddenly reduced, resulting in a sudden rise in component temperature, followed by rapid failure.

Most effective of all are direct spray systems, in which a fine mist of non-corrosive, non-conductive coolant is sprayed directly on the surface of the component, forming a liquid film that rapidly evaporates. The coolant vapor is extracted from the enclosure and condensed, rejecting heat to the surroundings. The problem? As we discussed above, many simulation tools are specifically designed to handle single-phase air-cooling and, at a push, simplified indirect liquid cooling (modeled using a source term or a boundary condition). If you want to explore any of the more advanced liquid cooling technologies, your simulation tool needs to be able to model multi-phase calculations, which include the interaction between air, liquid and various gasses, as well as boiling and phase change. Without this functionality, your simulations and your designs will be limited to simple, ineffective air-cooling. Other Advanced Physics Of course, it’s not all about cooling. Engineers in the electronics industry have a whole multitude of problems to deal with, to name but a few: • fan performance and acoustics (if you’ve ever been inside a datacenter, then you’ll know how important that is); • water intrusion; • dust build ingress and accumulation; • hydrogen build up (from battery decay). The benefit of employing a fully featured simulation tool is that, no matter how rarely these problems occur, your engineering software will allow you to solve them when they do. <

Fit for purpo

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My Electroni

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oftware: Can handle complex geom etries without gros s simplificati on Solves proble ms that span multiple length scales

Solves proble ms convection an that involve natural d radiation Allows me to simulate prob lems involving liq uids as well as gasses

i FOR MORE INFORMATION ABOUT CD-adapco PRODUCTS: www.cd-adapco.com/products

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..::FEATUREâ&#x20AC;&#x2C6;ARTICLE Automotive

InDesA came to the conclusion that there is a demand for a highly optimized virtual test environment that is fast, flexible and cost efficient in comparison with traditional physical testing.

InDesA is an engineering consultancy and services company with specialization on complex fluid flow and heat transfer simulation and analysis for industrial applications. Although the history of InDesA is still young, our leading engineers look back at 20 years of experience in the field of automotive and power train development. Besides we have developed simulation techniques for other competence fields like general aerospace, marine, energy and for the environmental sector.

InDesA Virtual Test Facility Center Dr. Gerald Seider - InDesA

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..::FEATURE ARTICLE Automotive

ABOVE Flow through a complete coolant circuit

TOP Combined generator/coolant pump from IGEL AG ABOVE Flow through the combined generator / coolant pump

The demands of modern vehicle design require that many components be designed and tested simultaneously. Almost all of these components need to be specifically optimized for their role in the particular vehicle design, and many utilize innovative technology. With little time for construction and testing of physical prototypes, along with the need for fast adaption of components due to changing module and system requirements, there is a compelling case for the introduction of more virtual testing at component level in vehicle development programs. The need for simulation in the “V-Model” Development Process The development of any vehicle takes several years, incorporating many thousands of hours of design and testing. To manage this process, most manufacturers of vehicles such as cars, buses and trucks have adopted the so-called “V-Model” development process. The V-model process starts with the design of the overall vehicle system. Once the system has been fully specified, the vehicle is divided into a series of modules. Each of these modules is essentially considered as a separate sub-system for design purposes (although in practice the many interactions between different modules must be accounted for). The final and most detailed part of the design stage involves the design of the individual components that make up the modules such as heat exchangers, pumps and turbochargers. Having reached the bottom of the “V”, the verification branch becomes active and the individual stages are subjected to testing, starting with component level verification, then advancing to the module and finally to the vehicle level verification. One of the most critical stages occurs as the process approaches the bottom of the “V”. Here, the vehicle components need to be designed and verified almost at the same time. While in the past it was often possible to select tried and tested “off-theshelf” components, the complexity of modern vehicles requires that almost every component should be specifically designed and optimized for the overall system. Put simply, this means there is no time to build physical prototypes and measure performance on test rigs. The only practical solution to this problem is the adoption of a “virtual test rig” in which numerical simulation of virtual prototypes takes the place of physical testing and validation. This becomes even more critical when dealing with innovative components that affect several parts of the system, such as the

combined alternator/water pump unit described below. Such a unit influences both the cooling and electrical systems of the vehicle, creating an interdependence between them. Therefore, the system designer requires detailed operating characteristics of both the alternator and the water pump, while on the other hand it is very difficult for the unit supplier to build a prototype if the system designer has not completely defined his requirements. This creates an “iterative loop” that must be quickly resolved. Here again, we think that a virtual test rig would be helpful and beneficial for the development of innovative components. The InDesA Virtual Test Rig InDesA came to the conclusion that there is a demand for a highly optimized virtual test environment that is fast, flexible and cost efficient in comparison with traditional physical testing. Such a virtual test center would be useful for performance prediction of standard automotive accessory units, producing performance maps for fans, pumps, compressors and heat exchangers. The Virtual Test Center would also be beneficial for functional testing & confirmation of larger engine and vehicle thermal systems such as coolant circuits, heat exchanger packs in the front-end of a vehicle, electronics cooling, and the cooling of battery packs. The figure above shows our main applications for accessory units such as cooling fans, compressors, coolant pumps and heat exchangers. For these, performance maps, e.g. pressure over volume flow rates for different fan or impeller speeds, are usually produced. Heat exchangers are slightly more complex as they feature two different fluids as well as heat transfer through the structure. For these, heat transfer and pressure loss maps are typically produced. The figure below shows more complex units, such as the water g

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..::FEATURE ARTICLE Automotive

ABOVE Fans, compressors, coolant pumps and heat exchangers are characterized by making a performance map.

Visit the link below for more AUTOMOTIVE stories:

www.cd-adapco.com/industries/automotive pump and heat exchanger being integrated with the coolant system, or different heat exchangers and a fan being grouped together into a front-end cooling pack. Those setups are used for functional testing and validation. Two more applications, which are similar to heat exchangers but with a more complicated heat flux path, deal with battery and electronics cooling. All of these applications are obviously very computationally intensive: in order to produce performance maps, many operating points need to be calculated in parallel. InDesA has therefore invested in a computer cluster with 112 nodes, which uses a high speed communication switch. This hardware allows us to easily outperform conventional test rigs with respect to operating time. At the heart of the virtual lab is STAR-CCM+, a comprehensive engineering physics simulation tool that provides an engineering process for solving problems involving fluid flow, heat transfer and solid stress. STAR-CCM+ is highly automated, which means that parametric design studies can be completed with little or no manual input. An additional module, the Facility Supply, is represented by 1D system models for the engine, coolant or lubrication system, and aims to enhance the components integrated environment by including the whole system. The underlying motive is to eventually be able to reproduce the system characteristics of the coolant circuit, so the number of operating points needed to generate a performance map can be narrowed down to where the pump actually operates. EGR Cooling Module Design In this first example, we are looking at a typical EGR (Exhaust Gas Recirculation – a technique used to reduce nitrogen oxide emissions) cooling module. There is one inlet and one outlet, for the exhaust gas and the coolant each, where mass flow rates and temperatures are prescribed. Also, the environment is defined in terms of temperature and heat transfer coefficients. With a GT-SUITE engine model, the characteristic flow rates and temperatures, or the pressure difference between the exhaust inlet and outlet as the EGR cooler connects the exhaust with the intake manifold, can be retrieved. With a GT-POWER model, the highly fluctuating gas flow can also be captured, which is essential in the heat transfer analysis. A few additional boundary conditions are needed for the positions of the bypass flap and the EGR valve integrated in the cooling module. The model setup can be done most efficiently in STAR-CCM+ where direct thermal fluid structure coupling (which includes all the details of the pipes or plates with fins or dimples, as well as details of flaps and hinges to account for flow leakage) can be used. The simulation results were as follows: the outlet temperature and pressure loss of the coolant could be predicted, as well as the areas where boiling is likely to occur. We could also predict the volume flow rates for the valve seat cooling and assess the flow uniformity. For the exhaust gas, the most important result was the prediction of the outlet temperature and the pressure loss. We also predicted the forces on the bypass flap, as sometimes flow leakage is the reason why targets

ABOVE More complex arrangements, where multiple components are combined, require more computer intensive treatment.

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are not fully met. Structural temperatures were computed everywhere (and most importantly in the valve seat area), which enabled a structural stress/strain analysis to be conducted to gain some insight into fatigue problems. Finally, the heat flux was computed from the exhaust through the structure to the coolant. By running enough operating points for the heat exchanger, we could calculate the Nusselt correlation for heat transfer and thus derive a full heat transfer map. Such correlations are usually needed for 1D system analyses. However, it should be stressed that a virtual test rig has more capabilities than just producing performance maps. The analysis of the results can highlight any weak points in the design and facilitate immediate remedial redesign. Innovative Pump Design Our second example deals with a combined generator/coolant pump designed by one of our partner companies, IGEL AG. This design has recently won the “award of innovation” granted by the Würzburger Automobil Gipfel 2010. It consists of a belt driven generator, a clutch, and an electric motor with a coolant pump at the end. The generator is water cooled with the help of a water jacket. The water pump can be driven directly by the generator shaft if the clutch is closed, in which case the electric motor is disengaged. If the clutch is open, the e-motor can drive the impeller independently, even if the engine is switched off. So, in the first case, we have a mechanical water pump, and in the second, an electric water pump. This is particularly useful for turbocharger cooling, which must continue after the engine has been switched off. For the design of this innovative pump, we had specific fluid mechanical design goals. We had targets for generator cooling, pump performance, and efficiency. We had to keep the pressure loss of the water jacket low to avoid degrading the pump efficiency. To achieve the performance target, we had to design a new high speed impeller as the gear of the belt transmission for generators is much higher than for conventional water pumps. For this particular case, we took over not only the task of predicting the pump performance, but also the design of the impeller, the volute, and the generator coolant jacket. This is a clear example of how the virtual test rig approach enables the direct interaction of design and verification. The challenge with marketing such a concept is that, as you approach different OEMs, each specifies a list of different wishes, requirements, and targets. This means that the generator/pump unit must be repeatedly adapted and redesigned in a very short time, before finally proving to the OEM that the component meets the required specifications. Cost efficiently, this can only be achieved within a virtual process where design and verification interact directly. With just a single fluid stream, the model is not too complicated, using a single inlet and a single outlet. For this purpose, the movement of the impeller does not need to be modeled explicitly and it is sufficient to use the computationally less expensive method of Multiple Reference Frames (MRF). The simulation results predicted the volume flow rate and the pressure rise for different pump speeds,

..::FEATURE ARTICLE Automotive

EGR Coolant flow

SYSTEM

VEHICLE

SIG

MODULE

as well as the hydraulic efficiency by determining the torque due to pressure and friction. We also predicted the onset of cavitation. For the water jacket of the generator, we calculated the pressure loss and heat transfer coefficient to assess the cooling capabilities. Finally, we extracted the pump performance map; affinity laws were helpful in completing this map. If a GT-SUITE model was added to the coolant system, we could derive the operating conditions under which the pump is balanced and establish where the pump would best operate. Accordingly, we could cut down the number of operating points, thereby saving a significant amount of computational effort and time. More Complex Systems Having investigated single accessory units, it can become informative to link them together. In this case, we combined a cooling fan with different heat exchangers to form a simplified underhood model for the investigation of a whole cooling module. For the fan, we can either use a 3D CFD model or derive a performance map and simplify the fan in the underhood model as a disc with a momentum source. As with the heat exchangers, we do not need to resolve the entire geometry but can use the Nu correlation derived by virtual testing or by conventional hardware testing. We came up with a useful test rig set-up to investigate the mass flow and heat transfer rates of the cooling module of a car whose front-end geometry is not yet known or decided. By using a detailed CFD model for the fan, we could also account for the flow interaction between the fan and the engine and asses how it downgrades the fan performance. Needless to say, we could easily shift the positions of the heat exchangers and the engine to adapt the model to changes in the engine compartment.

EGR Structural Temperatures

EGR Exhaust Gas Flow

RIF ICA TION

EGR Cooling Module Design

COMPONENT ABOVE The “V-Model” development process

design process The InDesA Virtual Test Facility Center is based around the principles of High Fidelity, Repeatability, and Comparability High Fidelity because we use high resolution CFD models to ensure the full detail of the geometry is captured (accounting for even the flow leakage in pumps, hinges, etc.). By exploiting the strength of the STAR-CCM+ physical model library, we are able to include radiation, two-phase for boiling, and, if needed, a kinematic module for pressure actuated flaps.

Coolant Circuit Design Another example of a useful combination of accessory units is the coolant circuit, whose 3D CFD model is principally made of the CFD models of a water pump and heat exchangers (coolant side only). To complete the model, the geometries of the engine water jacket, thermostat, connecting pipes, and hoses are needed. A 3D CFD model of a complete water jacket can be used to investigate the flow rates in the entire coolant system for different pump speeds and thermostat / valve settings. If the model is sufficiently detailed, it is also possible to investigate the filling procedure and de-gas behavior. Conclusion The InDesA Virtual Test Facility Center is an efficient and environmentally friendly concept. It is efficient because we built a standardized procedure for a defined set of applications. The virtual world allows us to easily customize those procedures to the specific needs and wishes of our customers. This is made possible by our computational test facility center, which is powered by over 100 processors, linked with a high performance communication and storage system, and tuned for optimal performance of STAR-CCM+. It is environmentally friendly because the cluster is cooled using only standard ventilation and no air conditioning. Considering that a single car radiator can discharge 100 to 150 kW into the environment, it is obvious that numerical simulation is far more energy efficient than the physical testing of prototypes. <

Repeatability because the CFD model of a test rig and the test object are packed and archived with all the results for reuse. Additional operating points can be run at request anytime in the future. Comparability because we want to be able to compare results at different stages of the prototype, using the same boundary conditions, solution method, and mesh resolution.

❐ FACT

i FOR more infoRMATION ABOUT InDesA, PLEASE VISIT: www.indesa.de/

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..::FEATURE ARTICLE Aeroacoustics

❐ FACT

DID YOU KNOW? What is the difference between a moonroof and a sunroof? Do you think that a moonroof is a sunroof operated by night or while listening to Michael Jackson’s music? Then this box out is for you! According to www. sunroofs.org, “Sunroof is the generic term used to describe an operable panel in a vehicle roof which can let in light and/or air”. It includes pop-up, spoiler, folding, topslider, panoramic, inbuilt, and removable panels. “Moonroof is a term created by Ford in the 70’s, yet is now used generically to describe glass panel inbuilt electric sunroofs.” In other words, a moonroof is just a type of sunroof. Almost disappointing…

Sunroof Buffeting & Acoustical Impedance of Flexible Structures Fred Mendonça & Deborah Eppel - CD-adapco

BELOW 3D Roof Panel Representation

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..::FEATURE ARTICLE Aeroacoustics

With the transport industry facing a continuing demand from customers and regulators to improve the aeroacoustic and vibroacoustics performance of their products, reducing flow-induced noise has become more relevant than ever. Traditional Fluid-Structure Interaction (FSI) CFD coupled methods have been judged too time consuming, technically challenging and/or computationally expensive to lend themselves to production level aeroacoustics analyses. However, by developing and commercializing a new fluid-structure integrated capability for aeroacoustics simulations with structural impedance effects, CD-adapco has shown that it is no longer the case...

The noise associated with sunroof (or side-window) buffeting is caused by unsteady flow over the sunroof opening interacting with the roof panel and radiating sound to the vehicle occupants.

Imagine sitting in your car on a sunny summer day, driving through the beautiful countryside and listening to your favorite program on the radio. Everything is perfect, you even have a full tank. The air outside is fresh and pure, and you decide to open the sunroof to make the most of this idyllic, if slightly clichéd, situation. As you do so, the sound of the radio gets drowned by the buffeting of the sunroof. You are now facing a difficult choice: listening to your favorite radio program without damaging your hearing, or breathing some fresh air? Sound familiar? You’re not the only one. Numerous car components produce a perceivable aeroacoustic signature. For example: External components such as side mirrors, A-pillars and windshield wipers: these directly excite the vehicle’s glass panels, which transmit noise to the driver’s ear; Under-the-hood turbo-machines such as the cooling fan and turbocharger: their noise can be heard above the idling engine; Ducting and climate control system components such as the blower fan and flaps: these create noise that is directed into the passenger compartment; Open apertures such as sunroofs and windows: these suffer buffeting caused by oscillation of the separated shear layer at the aperture leading edge. Automobile manufacturers and component suppliers are keen to demonstrate expertise in applied technologies for noise minimization. However, although CFD

aeroacoustics methodologies are well established, simulation has not yet been consistently adopted in production, design and development. Therefore, to prove CFD’s viability and reliability in the aeroacoustics field, there is a need to provide well validated, fast and repeatable methodologies across all these sectors. CD-adapco is pioneering aero-vibroacoustics methodologies, working with established experts and CFD-complementary software. While STAR-CCM+ has demonstrated direct coupling to industry-leading acoustic and vibroacoustic tools, one class of aero-vibroacoustic simulation is viable entirely within the STAR-CCM+ environment. We illustrate here a fully integrated flow-structures interaction as applied to sunroof buffeting. Simulating Sunroof Buffeting The noise associated with sunroof (or side-window) buffeting is caused by unsteady flow over the sunroof opening interacting with the roof panel and radiating sound to the vehicle occupants. One way to reduce the noise signature associated with this phenomenon is to add deflectors to change the flow pattern over the opening, often by introducing additional mechanical parts. Another way is to add flexibility to the sunroof panel by changing the material it is made of. In a recent experimental study [1,2] performed by the Aeroacoustics Consortium of German Automotive Manufacturers, a series of experiments were conducted on the SAE Body, modified to include a sunroof and passenger cavity volume. The results established that the aeroacoustics buffeting noise signature at the driver’s ear location is significantly affected by material damping properties of the panels used in the model. g

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..::FEATURE ARTICLE Aeroacoustics

ABOVE Impact of the vortex on the rear roof panel behind the sunroof opening

RIGHT Modified SAE body with sunroof aperture, internal passenger cavity and flexible roof panel

Visit the link below for more Automotive stories:

www.cd-adapco.com/industries/automotive

Validation tests using CD-adapco’s flagship software, STAR-CCM+, were conducted, initially assuming the model structure to be perfectly rigid. Results proved to be excellent through most of the vehicle operating speed range, with the exception of a minor over-prediction of the overall sound pressure level (OASPL) over a critical speed range, where the material damping effects were observed to be most pronounced. This over-prediction was put down to the initial rigidity assumption and was therefore not considered to be a major concern. Simulation with Impedance Effects CD-adapco decided to re-run the simulations while taking into account the material structural impedance effects. Using STAR-CCM+, a series of fully compressible DES calculations were performed at a nominal vehicle speed of 80 kph. This combination, importantly for this application, takes into account the flow and acoustical feedback which is a strong mechanism at this speed. Approximately 3 million cells were used to represent the half-body, including about 500,000 cells to model the solid. STAR-CCM+ is unique in its ability to perform two-way coupled fluid-solid interaction: it uses a Finite Volume Solid Stress solver implicitly integrated with the Finite Volume Flow solver to analyze the acoustical damping effects of flexible materials. The solid is meshed in a similar way to the flow volume around it. Built-in meshing algorithms allow for conformal meshing between the fluid and solid domains. The mesh is allowed to deflect if the displacement of the solid is significant compared with the local grid resolution. Momentum and energy are exchanged between the fluid and solid systems. This directly accounts for energy extraction from the fluid system to deflect the solid if the conditions are conducive. Three material types were assessed: aluminum, Perspex and MDF (Multi-Density

wood Fibre). In the Finite Volume Solid Stress model, the Young’s modulus, Poisson’s ratio and density were changed according to the respective material. The effects of the material properties on the roof panel deflection were found to be significant. Perspex and plywood deflect by almost two orders of magnitude more that the baseline aluminum. As energy absorption due to the mechanical movement of the roof panel changes the perceived acoustic pressure at the driver’s ear location, this shows that the driver’s experience will be much quieter with a sunroof made of Perspex than with an aluminium panel. Conclusion By working closely with the transport industry, CD-adapco provides validated tools to predict and design against aeroacoustical effects early in the design process. One industrial aeroacoustics case study, among a multitude of other possible applications in the transport industry, has been briefly described in this article. The results proved to be accurate and the study helped illustrate how a deeper understanding of acoustical phenomena can be gained through the use of STAR-CCM+, thereby enabling a higher degree of engineering value to be added while reducing costs and timescales in the CAE process. For more information about methodologies and best practices for aeroacoustics simulations in the automotive and aerospace sectors, please refer to [3,4]. Additional case studies such as the airframe noise simulation of a complex nose landing gear, the aeroacoustics study of an avionic cooling rack in an Airbus cockpit, and the analysis of the fan noise signature in the presence of gusts are also described. <

i KEEP up to date with the latest star-ccm+ release: www.cd-adapco.com/products/star_ccm_plus

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..::FEATURE ARTICLE Aeroacoustics

ABOVE Instantaneous velocity field surrounding the panel: the flow is highly unsteady and leads to the generation of vortices.

ABOVE Roof Panel Deflection for the three different materials

ABOVE Acoustic Pressure (Pa) at the driver’s ear location for the three different materials

REFERENCES: [1] “Investigations of Sunroof Buffeting in an Idealised Generic Vehicle Model -- Part II: Numerical

Simulations”, M. Islam et al., presented at the 29th AIAA Aeroacoustics Conference, May 5-7 2008,

Vancouver, Canada, AIAA-2008-2901

[2] “Numerical and Experimental Investigations of the Noise Generated by a Flap in a Simplified

HVAC Duct”, Anke Jäger et al., presented at the 29th AIAA Aeroacoustics Conference, May 5-7

2008, Vancouver, Canada, AIAA-2008-2902

[3] “Efficient CFD Simulation Process for Aeroacoustic Driven Design”, Mendonça et al., presented at

ABOVE Pressure Spectra (dB) at the driver’s ear location for the three different materials. With Perspex, the noise level which the driver hears reduces by up to 10dB (decibels) at the peak frequency compared with Aluminium. This figure illustrates how the flexibility of the roof panel is able to absorb acoustical energy to quieten the passenger experience.

the II SAE Brazil International Noise and Vibration Congress, October 17-19 2010, Florianopolis,

Brazil, SAE-2010-36-0545

[4] “Aero-Vibroacoustics Fully Coupled Prediction of Panel Impedance Effects in Sunroof Buffeting”,

Mendonça et al., presented at the 17th AIAA/CEAS Aeroacoustics Conference (32nd AIAA

Aeroacoustics Conference), June 5-8 2011, Portland, Oregon, AIAA-2011-2817

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..::FEATURE ARTICLE Automotive Visit the link below for more stories like this:

www.cd-adapco.com/industries/automotive

The Vienna University of Technology (TU Vienna) is located in the heart of Europe, in a cosmopolitan city of great cultural diversity. For nearly 200 years, the TU Vienna has been a place of research, teaching and learning in the service of progress. The TU Vienna is among the most successful technical universities in Europe and is Austria’s largest scientific-technical research and educational institution.

CFD Helps Make Engines More Efficient Thomas Lauer - Vienna University of Technology, Austria

The development of internal combustion engines with lower emissions and fuel consumption requires an early knowledge of the combustion mechanisms. Therefore, a method was developed at the Institute for Powertrains and Automotive Technology at the Vienna University of Technology that allows the prediction of the combustion stability based on simulations with STAR-CD. Reducing the green house gases In the recent past, the public’s attention has become increasingly drawn to the consequences of environmental pollution caused by traffic. In particular, the influences of so-called “greenhouse gases” on the future climate have been discussed intensively. The European Union, for example, is preparing a restriction of the CO2-carfleet-emission of 120 g/km by 2012. To meet these demands, automive companies have been investing considerable efforts to make their cars more efficient and less thirsty. For gasoline engines, the recirculation of inert exhaust gases and their mixing with fresh air is an efficient measure to reduce the fuel consumption. Unfortunately, the presence of inert gases makes the ignition of the mixture less stable. Therefore, an optimal control of the in-cylinder flow, the turbulence and the fuel preparation in the engine’s combustion chambers is necessary to achieve high residual gas recirculation rates and the best fuel economy. This is where CFD comes into play!

STAR-CD and es-ice make the combustion chamber accessible All the necessary models to simulate the turbulent flow field and mixture preparation in the combustion chamber are implemented in STAR-CD. In the following, the turbulent flow field was modeled with the k-ε turbulence model for high Reynolds-numbers and the fuel injection with the Lagrangian approach. In addition, the expert system es-ice allows us the opportunity to create moving meshes that take the motion of the valves and the piston into account. Care has been taken to model the spark plug in as much detail as possible, in order to obtain accurate results for the flow field where the spark ignites the mixture and the flame propagation starts. The accompanying image shows typical results of a transient in-cylinder simulation. The flow field during the engine’s intake stroke, as well as the distribution of fuel, residual gas and turbulence in the combustion chamber at the time when the spark ignites the mixture can be observed. On the other hand, a more unstable combustion can be observed at the engine test bench when the residual gas concentration is increased and finally leads to misfiring. For a prediction of the ignition limit, and therefore the maximum acceptable residual gas recirculation rate, it is necessary to find a “link” that allows an interpretation of the mixture properties calculated with STAR-CD to explain the unstable combustion oberserved at the engine test bench. Turbulent and chemical scales characterize the premixed flame This link was found by analysing the turbulent and chemical scales for premixed flames. A turbulent flow field consists of a variety of turbulent structures, so called eddies, that influence the flame immediately after ignition. The big eddies, with a size larger than the thickness of the flame front, wrinkle and extend its surface. The small eddies, with a size comparable to the flame front thickness, penetrate the reaction zone and increase the strain, species transport and heat flux. Both effects have a characteristic impact on the flame propagation and extinction.

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..::FEATURE ARTICLE Automotive

ABOVE Ignition limit for the investigated engines in the BORGHI-diagram

ABOVE Comparison of the measured and predicted residual gas recirculation rates

These complex interactions and their influence on the ignition stability can be described with dimensionless parameters, such as the Damköhler-number, which relates the turbulent and chemical scales and can be derived from the simulation results of the turbulent flow field. Typical input data are the pressure, the temperature, the turbulent kinetic energy, the residual gas concentration and the local air/fuel ratio. However, to compute the numerous equations efficiently, an automated postprocessing was necessary. The application of STAR-CD macro functionality proved to be a good approach for this task. Thus, a macro was developed to carry out the necessary computations and to store the additional data in files for further analysis. A limit for a stable ignition By applying this methodology to two gasoline engines with different injection concepts and in-cylinder flows, a limit for a stable ignition could be determined. The dimensionless parameters that were derived from the simulation results were plotted in the BORGHI-diagram, which allows a visual representation of the premixed flame characteristics in relationship with the turbulent and chemical scales (shown in accompanying image). The straight lines of constant Damköhler- and turbulent Reynolds-numbers are included in the diagram. All simulations were carried out at an operation point where the engines revealed

ABOVE Results for the turbulent flow field during aspiration and ignition

a limit for a stable combustion on the test bench. It could be shown that the Damköhler-number describes the ignition limit satisfactorily. It must not drop below a value of 12.5 to “keep the fire burning” in a stable way. A comparison with results from the engine test bench regarding the maximum acceptable residual gas recirculation rate that still enables a stable ignition showed a good agreement with the predictions of the numerical method, as seen in the graph. Conclusion A recirculation of residual gas helps to improve the fuel economy of gasoline engines. To achieve a stable ignition with high residual gas concentrations in the combustion chamber, a proper prediction of the numerous interactions between the turbulent flow field and the initial flame is necessary. Based on the simulation results from STAR-CD, dimensionless parameters have been computed to characterize the behavior of the premixed flame after ignition. The modeling capabilities of es-ice and the macro functionality of STAR-CD helped to solve this task efficiently. A good correlation with observations at the engine test bench was found for the allowable residual gas recirculation rates. Thus, STAR-CD contributed to an improvement of engine’s fuel economy and emissions. <

i FOR MORE INFORMATION ABOUT The Vienna University of Technology: www.tuwien.ac.at

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..::FEATUREâ&#x20AC;&#x2C6;ARTICLE Turbomachinery

Turbocharger Analysis Dr. Richard Johns - CD-adapco

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..::FEATUREâ&#x20AC;&#x2C6;ARTICLE Turbomachinery

Through the enhanced analysis capabilities of its STAR-CCM+ CFD software tool, CD-adapco is providing a boost to turbocharger technology in the 21st century. Although recovery of exhaust gas energy using turbochargers was first applied nearly 100 years ago and has been in widespread use in the heavy-duty diesel market ever since, it is only in recent years that turbocharging has spread to mass production vehicles in smaller engines. The phenomenal market growth, first in passenger car diesel engines and more recently in downsized gasoline engines, has been driven largely by the efficiency gains, and hence CO2 benefits, that can be realized. Plus, Formula 1 will be returning to turbocharging for the 2014 season.

situation when there is no longer any flow through either the compressor or turbine, has the potential to damage not only the turbocharger, but also other components in the underhood environment. Non-metallic components such as electrical connectors, the wiring harness, rubbers, and composites are particularly vulnerable. The powerful conjugate heat transfer modeling capabilities available in STAR-CCM+ provides a means to simulate the transient flow and thermal fields, including the structure, within the entire engine compartment. In turn, this allows a quick assessment to be made as to whether damage will occur in the worst of situations.

The accuracy of STAR-CCM+ enables the effects of a non-ideal inlet geometry to be compared with the uniform inlet flow condition.

Modern turbocharging, however, is much more complicated than simply plumbing a turbocharger into the intake and exhaust system and leaving it to its fate. Multiple turbos, variable geometry, wastegate, bypass and integration into the engine manifold and engine management system coupled with high operating temperatures (>1,000Â°C in gasoline engines) in an already overcrowded underhood area provide serious challenges for powertrain, installation, and calibration engineers. To address thermo-fluid-structural issues related to turbocharging, CD-adapco has developed a range of solutions using STAR-CCM+. Packaging constraints rarely allow an ideal, uniform flow entry to the compressor and this can have a detrimental effect on the map. The accuracy of STAR-CCM+ enables the effects of a non-ideal inlet geometry to be simulated and compared with the ideal, uniform inlet flow condition. This provides a means to quickly assess alternative ducting arrangements and the effect on compressor performance. Heat transfer is a major issue for turbocharged engines. Heat transfer from the turbine to the compressor is detrimental to engine performance, but heat transfer from a hot turbo during a transient operation, for example a key-off

Last but by no means least, high-frequency turbocharger noise can be intrusive to occupants and those outside the vehicle, particularly during a load change. STAR-CCM+ has a comprehensive capability to calculate the noise sources originating from the rotation of the rotor and its interaction with other components and determine the sound pressure level in the far field. <

i Dr. Richard Johns, vice president of engine development, CD-adapco EMAIL: richard.johns@cd-adapco.com

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..::FEATURE ARTICLE Turbomachinery Visit the link below for more turbomachinery stories:

www.cd-adapco.com/industries/turbomachinery

ABOVE Pressure and suction surface pressure profiles, non transition calculation, hex mesh, C3X Case 1

LEFT C3X vane geometry and cooling hole arrangement and inlet temperature

Validation of Blade Cooling on the NASA C3X Turbine - Polyhedral Meshing & Transition Modeling James Clement, Fred Mendonça - CD-adapco

The NASA C3X internally cooled turbine blade is a well documented [1] case for validation of Conjugate Heat Transfer (CHT). The following analysis demonstrates two key features of STAR-CCM+: multi-domain polyhedral meshing, which automatically builds continuous meshes between the solid, external and internal flow volumes, and transition modeling, which enhances the predicted heat transfer distribution, especially on the blade suction side. Several studies [2,3] using commercial codes have reported blade cooling validation results on a turbine. This article demonstrates the use of STAR-CCM+’ capabilities such as polyhedral multi-domain meshing and transition modeling in a similar validation case. Furthermore, due to uncertainties in the experimental turbulence levels upstream, the sensitivity of the surface heat transfer to the inlet turbulence viscosity ratio is assessed. The C3X experiment comprises of three linear cascade vanes cooled internally by 10 circular parallel holes running through from hub to shroud; measurements were taken on the center vane. The present methodology was validated against a case operated at a chord-based Reynolds number of 2.0 million, with an inlet total pressure and temperature of 3.217 bar and 783 K, the exit Mach number being measured as 0.9. The internal holes were supplied independently with different mass flows for which, unfortunately, the inlet temperatures were not recorded in the original measurements. The figure on the right and the accompanying table summarize the vane dimensions and cooling holes’ inlet temperatures.

ABOVE Mesh, domain, and near wall resolutions

Computational Setup The results from two different mesh types, a topologically block-structured hexahedra and polyhedra, were compared. In both cases, since the vane geometry is a linear extrusion, 20 equally spaced mesh layers were used in the 7.62 cm between the hub and the shroud. All results herein are reported for the mid-span section where the flow is nominally two-dimensional and unaffected by end-wall effects. y+ values were found to be less than 1 everywhere over the vane surface for both meshes. The inlet and outlet to the domain were placed 14 cm upstream and

downstream of the vane leading and trailing edges, respectively. Both hexahedral and polyhedral meshes contain just over 1 million cells (~800 k in the external flow, ~150 k in the solid and ~10 k in each hole). Two turbulence models were assessed. The first is a standard two-equation k-ω-SST model, with implicit low-Re near-wall attributes but with no special laminar-to-turbulent transition features. The second contains a correlation-based modification, referred to as the γ-Reθ model from Menter-Langtry (2004).

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..::FEATURE ARTICLE Turbomachinery

ABOVE Normalized wall heat-transfer: no-transition (top), transition (bottom)

ABOVE Transition model normalized heat-transfer sensivity to inlet turbulent viscosity ratio, TVR: from 40% to 70% (bottom)

A transport equation for intermittency, γ, tracks the likelihood of the flow to be locally laminar (value 0.0) or turbulent (value 1.0) whereas the transport equation for the transition Reynolds number, Reθ, uses experiment correlations to feed back to the γ-equation source terms when a transition is adjudged to occur. Malan [4] has published the two experimental correlations usually missing in the standard references to the model. Malan’s calibrations are performed on many standard transition test cases, including the ECROFTAC T3-series and the fixed correlations extensively validated on industrial cases. The inlet turbulence intensity in this experiment was set to 8.3% as recorded in the experiment. The inlet turbulence length scale (inlet turbulence viscosity ratio) was not measured; therefore this validation exercise takes the opportunity to test the modeling sensitivities to inlet turbulence length scales.

measured trend in the form of increasing heat transfer subsequent to transition, except that the transition length is predicted to be too short. In principle, the model correlation length [4] may be tuned to improve this predictive trend. On the pressure surface, the heat transfer levels are lowered consistently with the reduced levels at the stagnation point. The wiggles close to the trailing edge on both suction and pressure surface are a manifestation of the effect of the internal blade cooling holes. The figure above right shows the sensitivity of the transition model predictions to the inlet turbulence viscosity ratio on the polyhedral. The main differences are observed in the shift of overall levels of wall heat-transfer below 50%, becoming relatively insensitive above 50% TVR.

Discussion of Results The hexahedral mesh pressure coefficient over the pressure and suction surfaces compared favorably with the measurements and was insensitive to inlet turbulence length scales. The pressure profile was equally insensitive to the transition model in the polyhedral mesh. Conversely, the prediction of the wall heat transfer coefficient was found to be strongly dependent on the use/non-use of both the transition model and the inlet turbulence length scale. The figure above left compares the non-transition/transition model heat transfer predictions on the hexahedral mesh. The transition model has the effect of suppressing the over-penetration of turbulence within the boundary layer; the effect at the leading edge is to reduce the heat transfer at the stagnation point. The levels here still continue to be higher than the measured values, but we shall see later that the heat transfer at stagnation is closely related to the upstream turbulence intensity. The transition model clearly delays the onset of the boundary layer transition on the suction surface until around 40% of the chord, consequently reducing the wall heat transfer in line with the measurements. The predictive trend follows the

Conclusion We have demonstrated that there is sensitivity of the heat-transfer solutions to the levels of incoming turbulence. Therefore, it is very important to know the upstream turbulence levels from measurements as a requirement to perform well qualified CFD validation studies. Furthermore, we have shown a validation of STAR-CCM+ for internally cooled turbine blades. Agile meshing capabilities using polyhedral cells for multiplyconnected domains and advanced physics models cater for complex phenomena including surface heat transfer. The process affords significant productivity gains through integration and automation. < REFERENCES: [1] Hylton L.D., Mihelc M.S., Turner E.R., Nealy D.A., York R.E., (1983), “Analytical and Experimental

Investigation of a Convection-cooled Gas Turbine Vane”, 59 Congresso Nazionale ATI

[3] Luo J., Razinski E.H., (2007), “Conjugate Heat Transfer Analysis of a Cooled Turbine Vane using the V2F

i MORE INFORMATION ON TURBOMACHINERY info@cd-adapco.com

Evaluation of the hHeat Transfer Distribution over the Surfaces of Turbines Blades”, NASA CR 168015

[2] Canelli C., Sacchetti M., Traverso S., (2004), “Numerical 3-D Conjugate Flow and Heat Transfer

Turbulence Model “, Journal of Turbomachinery, Oct 2007

[4] Malan P., Suluksna K., Juntasaro E., (2009), “Calibrating the γ-Reθ Transition Model for Commercial

CFD”, AIAA-2009-1142-298, 47th AIAA Aerospace Science Meeting, Jan 2009

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..::FEATURE ARTICLE Turbomachinery ❐ FACT

TIME SAVING The unsteady, time-accurate runs were computed on a domain which included all three stator and four rotor passages to satisfy periodicity of flow. These runs took a total of approximately 20 hours of CPU time. In comparison, the CPU time needed for the HB computations was less than one hour retaining three harmonics at seven time levels. That’s 19 hrs of savings in computational time for a solution of reasonable accuracy for this case!

Visit the link below for more turbomachinery stories:

www.cd-adapco.com/industries/turbomachinery

Harmonic Balance Method: A Break From Traditional Simulation of Turbomachinery Flows Fred Mendonça & Prashanth Shankara - CD-adapco

Numerical Simulation of Turbomachinery flows are among the most complex computations performed in the world of Computational Fluid Dynamics (CFD). CFD applied to Turbomachinery has come a long way from the inviscid 2D blade-toblade methods of the 1960’s and recent developments have ensured that numerical simulation plays a major role in turbomachinery design. CD-adapco has more than 30 years of expertise in developing cutting-edge simulation capabilities for the turbomachinery industry, the most notable and recent of which is the Harmonic Balance (HB) method. To understand the need for Harmonic Balance, a little insight into the world of turbomachinery design with CFD is needed. In general, turbomachinery devices are multi-stage with unequal pitches for stators and rotors, and a majority of the flows highly unsteady in nature. The most common simulation methodology is steady-state simulation, which is computationally inexpensive but introduces approximations in the solution. Even though turbomachinery flows are inherently unsteady due to the relative motion of rotors and stators, computing an unsteady solution is expensive and is often unsuitable in a short design cycle. The choice between steady-state and transient methods depends on the right balance between computational cost, accuracy and efficiency. It is clear that the turbomachinery industry would benefit from a balance between the two approaches – a computationally efficient solution that accounts for the unsteady nature of the flow. The nonlinear HB method is an entirely new computational approach, offering the best of both worlds specifically for periodic flows. With applications in the compressible domain ranging from aerodynamics to blade-to-blade acoustic interactions in devices such as compressors, turbines, fans and wind turbines, the HB method is a cost effective, accurate and efficient choice for unsteady flows. Harmonic Balance Method Implementation in STAR-CCM+ The HB method in STAR-CCM+ is a full decomposition of the Navier-Stokes equations in the frequency domain. The unsteady, transient flow is represented

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in the frequency domain as a Fourier series in time. All transport equations for momentum, energy and turbulence are decomposed into the frequency domain on the basis of fundamental driving modes, usually a blade-passing frequency or repeating wake modes. Steady-state equations representing the unsteady solution at discrete time levels in a single unsteady period are solved to obtain the Fourier coefficients. The number of time levels required depends on the number of modes retained in the problem. The steady state solution in every time-level is implicitly coupled at the periodic boundaries by the physical time derivatives. The linear system is then subjected to approximate factorization to achieve implicit coupling between time levels. Validation Study The nonlinear HB method implementation in STAR-CCM+ has been validated recently by numerical simulations of unsteady, rotor-stator interactions [1]. The results were compared against those from a full unsteady, time-accurate simulation and found to be accurate with significant savings in computational cost and efficiency. The validation was conducted on a 2D compressor stage model with three stator blades to every four rotor blades as described by Ekici and Hall [2]. The first stator and second rotor of the five stages from this configuration were considered and the computational mesh, generated in STAR-CCM+, is shown in the accompanying image. An axial gap of 0.25 times the aerodynamic chord of the rotor separates the two blade rows and the Mach numbers at the inlets of the stator and rotor are 0.68 and 0.71 respectively. A static-to-total pressure ratio of 1.2 exists across

..::FEATURE ARTICLE Turbomachinery

the stage. Complex periodicity boundary conditions at the periodic boundaries are applied in the rotational direction, which enables the reduction of computations to a single passage in each row, decreasing computational cost. The solutions at all time levels are coupled to one another through these periodic boundary conditions. The inlet and outlet of the domain are located very near the leading and trailing edges of the outermost blades. These boundaries are treated as non-reflecting, farfield boundaries, thereby preventing unsteady numerical disturbances from reflecting back into the computational domain and reducing the size of the computations. Multi-stage coupling between rows is achieved by applying inter-row boundary conditions at the interfaces between various rows. In the Euler computations from the HB method, one, two and three harmonics are retained for the blade passing frequencies in the stator and the rotor. A cell-centered, polyhedral-based, finite-volume discretization of the governing equations is used with flux-difference splitting and linear reconstruction of variables. The accompanying image shows the instantaneous pressure contours within the compressor stage from the HB method, with computations being carried out only on the center blade passage and solutions in the upper and lower passage phase shifted, based on the center passage.

The solution from the HB method agrees well with the unsteady solution, while the steady state solution has small differences due to nonlinear effects. The magnitude and phase of the 1st mode of the unsteady pressure of the stator is also computed from the HB method. These results are compared with the time-domain solutions in the image below center. The unsteady pressure has a magnitude of about 10% of the mean and the HB results vary by only 2% of the mean, suggesting that the results show good agreement. Similar comparison for the rotor (figure below right) shows that there is more variation near the trailing edge but the results are of reasonable accuracy. Thus, the implicitly coupled nonlinear HB method can provide solutions of reasonable accuracy compared to a time-accurate approach, while saving significant computational time. <

ABOVE Computational Mesh for the 2-D Compressor Stage in STAR-CCM+

REFERENCES:

Results The comparison of the mean pressure distributions on the stator and rotor from the three HB computations with results from the traditional, unsteady, time-accurate runs are shown in the image below left. Results from a steady state solution based on a mixing plane approach, where the HB balance solver is used with zero harmonics to compute the flow through two blade rows, are also shown.

ABOVE Mean Pressure Distribution on Stator (top) and Rotor (bottom) from HB Method and Full, Unsteady Solution

[1] Weiss, J.M., Subramanian, V., and Hall, K.C., 2011, “Simulation of Unsteady Turbomachinery Flows Using an Implicitly Coupled Nonlinear Harmonic Balance Method”, GT2011-46367, June, 2011. [2] Ekici, K., and Hall, K. C., 2007. “Nonlinear Analysis of Unsteady Flows in Multistage Turbomachines Using Harmonic Balance”. AIAA Journal, 45(5),

ABOVE Instantaneous Pressure Distribution in the Compressor Stage from HB Method

May, pp. 1047–1057.

ABOVE Magnitude (top) & Phase (bottom) of the 1st Mode of Unsteady Pressure on Stator – HB and Time-Accurate Unsteady Solution Comparison

ABOVE Magnitude (top) & Phase (bottom) of the 1st Mode of Unsteady Pressure on Rotor – HB and Time-Accurate Unsteady Solution Comparison

i SIMILAR STORIES CAN BE DOWNLOADED ON OUR WEBSITE: www.cd-adapco.com/downloads

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..::FEATURE ARTICLE Aerospace

LEARJET 60 - SPECIFICATIONS Manufacturer Bombardier Aerospace Class Twin-engine Corporate Jet Crew 2 Passengers Max. 8 Propulsion 2 Turbofan Engines Max. Thrust 4,600 pounds (20.46 kN) Engine Model Pratt & Whitney PW305A Engine Power (each) 23,2 kN 5225 lbf Speed 887 km/h 551 mph Service Ceiling 15.545 m 51.000 ft Range 4.441 km 2.760 mi.

Empty Weight 6.641 kg max. Takeoff Weight 10.659 kg

14.641 lbs 23.500 lbs

Wing Span Wing Area Length Height

13,40 m 24,6 m² 17,80 m 4,36 m

44,0 ft 265 ft² 58,4 ft 14,3 ft

First Flight Production Status

January 18, 1990 Still in production

❐ FACTS

After evaluating a number of options, Raisbeck Engineering decided to invest in STAR-CCM+ due to its ability to address all of Raisbeck’s requirements.

Raisbeck Engineering designs, develops and produces unique solutions through advanced technology and innovative engineering that enhance the performance and operational efficiency of aircraft. www.raisbeck.com

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INTERNAL Cabin length Cabin max. width Cabin width (floorline) Cabin height Floor area Total volume

17.67 ft 5.95 ft 3.9 ft 5.71 ft 68.9 ft2 453 ft3

5.39 m 1.81 m 1.19 m 1.74 m 6.40 m2 12.80 m3

..::FEATURE ARTICLE Aerospace

Designing a drag-free storage locker for the Learjet 60 Davud Kasparov - Raisbeck Engineering Inc.

The Aft Fuselage Locker for the Learjet 60 marks a milestone for Raisbeck Engineering. The program is the first to use an in-house CFD capability at Raisbeck, and also the first Raisbeck product for the Learjet 60. For this program, a zero-drag penalty goal was set, achieved in simulations and validated in flight test. A market study conducted by Raisbeck Engineering Inc. revealed that increased baggage capacity was the number one request from Learjet 60 operators. As a result, Raisbeck Engineering decided to pursue the opportunity of creating an Aft Fuselage Locker (AFL) similar to the Raisbeck’s AFL for the Learjet 30-series aircraft. Six months before launching the Learjet 60 AFL program, Raisbeck Engineering made a decision to stop outsourcing CFD and bring it in-house in an effort to expand hands-on knowledge, reduce development time, and increase control of priorities. After evaluating a number of options, Raisbeck Engineering decided to invest in STAR-CCM+ due to its ability to address all of Raisbeck’s requirements. After becoming familiar with the package, the next step for Raisbeck Engineering was to obtain a digital model of the Learjet 60 geometry. Geometry To ensure the aircraft was accurately represented, Raisbeck Engineering invested in digitizing a full-scale Learjet 60. To accomplish the task, white light interferometry scanning was used. The technique involves projecting fringe patterns onto the aircraft from varying distances, capturing resulting interference patterns g

i DOWNLOAD THE LATEST AEROSPACE REPORT:

ABOVE Learjet 60 being prepared for white-light scanning with reference markers

www.cd-adapco.com/downloads/special_reports

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..::FEATURE ARTICLE Aerospace

ABOVE Learjet 60 with Raisbeck Aft Fuselage Locker on first flight

and intensities with multiple cameras, and finally resolving the geometry by reducing data in the frequency domain. The resulting point cloud, representing half of the aircraft to an accuracy of under 0.01 inches, consisted of over 35 million points. Surfaces were then lofted, conforming to the scan data while simplifying the geometry by excluding minor details such as rivets, gaps, small antennas, etc. With the aircraft geometry in hand, brainstorming could begin. Goals & Constraints Before the conceptual design of the aft fuselage locker (AFL) shape began, physical constraints were set to, among other things, ensure the AFL did not strike the ground during take-off rotation. Additionally, the target cargo capacity was set at 300 lbs and 25 cubic feet. Most shapes considered for the AFL could be split into 3 categories with varying degree of cargo capacity: those that ended with a fin, those without a fin, and hybrids (see image for a comparison of the shapes). With each concept, attributes such as cargo volume, external wetted area, and ease of manufacturing were considered and weighed against the results of CFD simulations. Performance To evaluate the aerodynamic performance of each concept, a range of cruise conditions was picked from two sources, the aircraft flight manual and operator feedback. At each flight condition, the aircraft with a concept shape attached was trimmed in angle of attack for the target lift and with the incidence of the horizontal tail for a zero pitching moment about its center of gravity. The parameter summarizing overall aerodynamic performance, used to compare all configurations with respect to baseline, was the lift to drag ratio, or L/D. Pressure distributions were monitored to ensure high suction peaks were not introduced, as shown in accompanying image.. Simulation In terms of simulation, all analysis was conducted in STAR-CCM+. Simulations were run in steady state with Menter’s SST K-ω turbulence model, which previously had been shown to produce good agreement in internal validation studies. In order to meet strict deadlines, a mesh consisting of approximately 6.5 million polyhedral cells was used to enable the calculation of a trimmed flight condition in less than 48 hours on a 24-node cluster. Results: CFD Analysis revealed that at all cruise conditions, all concepts showed an absolute change in L/D of less than 1% when compared to the baseline configuration. This was within the accuracy found in earlier validations. Out of curiosity, an aerodynamically dirty shape was simulated that showed a change in L/D of -4% (increase in drag). With the knowledge gained through CFD simulations, the design candidate with attributes of a large cargo capacity and a simple manufacturing process was chosen to be flight tested.

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Results: Flight Test The main goal of flight test was to validate the zero drag of the AFL. As a result, only the external shape of the locker was required. To build the flight test article, a single block of high density foam was machined as a master. Eight plies of pre-impregnated composite were then laid up, with honeycomb cores and bulkheads added in crucial areas, and cured to yield a shape measuring 24 feet in length. Flight test results indicated that STAR-CCM+ predictions agreed within acceptable accuracies to the flight test measurements, and that the goal of zero-drag penalty was achieved. Conclusions Raisbeck Engineering has digitized a Learjet 60 aircraft, designed a drag-free locker with the help of STAR-CCM+ and confirmed results in flight test. The Aft Fuselage Locker for the Learjet 60 is now in the detailed design phase where the internal mechanics, manufacturing, and other details are being addressed. When complete, this post-production and aftermarket modification will not only enable aircraft operators to carry more baggage but will also enhance the aircraft’s performance. <

BELOW Lift to drag ratio comparison between CFD and flight test results

..::FEATUREâ&#x20AC;&#x2C6;ARTICLE Aerospace

BELOW CAD model of the Raisbeck AFL in detailed design phase

BELOW Pressure distribution comparison, side view: finless locker (bottom) vs. baseline (top) at Mach 0.72. Some aircraft components were visually omitted for clarity.

With the knowledge gained through CFD simulations, the design candidate with attributes of a large cargo capacity and a simple manufacturing process was chosen to be flight tested.

ABOVE Generalized AFL candidate shapes, viewed upside down: finned (left), finless (center), and hybrid (right)

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..::FEATURE ARTICLE Aerospace

From Design Challenge to Flying UAVs in Fifteen Weeks Prashanth Shankara - CD-adapco

Fifteen weeks! That’s all it took for a group of senior undergraduate students from the University of Washington’s Aerospace Engineering department to design, test, and build a commercial quality small Unmanned Aerial Vehicle (UAV) for research focusing on low-speed flight characteristics and engine noise-shielding of supersonic flight vehicle configurations.

Dr. Eli Livne, Professor of Aeronautics and Astronautics at the University of Washington, has been leading the senior capstone design project for more than a decade with the help of Chester (Chet) Nelson, an Affiliate Associate Professor and a Boeing Technical Fellow. The motivation for the program was to provide students with ‘a complete, deep design experience’. In the 2010 academic year, the goal of the project was to design, analyze, build, ground and flight test a UAV representing a commercial supersonic aircraft configuration, with focus on low speed handling characteristics, low sonic boom design, and noise shielding of the jet engine. Armed with just mission requirements and the design challenges for 2010, the team of seniors from the Aeronautics and Astronautics department of the University of Washington surpassed all expectations with a finished prototype that was one of the most complex and sophisticated of its kind. The project was completed within schedule and to budgetry constraints that would impress any aerospace industry leader. Students with no previous CAE/Testing/Manufacturing experience were given four months to develop the design into a flying prototype. If it sounds challenging, it is! The team of 32 seniors was split into groups which were tasked with: Computer Aided Design (CAD), aerodynamics and Computational Fluid Dynamics (CFD), wind tunnel testing, stability and

control, propulsion, acoustics, systems, structures, weight & balance, and construction. Over the course of the project, the students had the opportunity to experience and gain insight into major elements of the design process in the real world: teamwork, information exchange and communication, systems engineering, multidisciplinary interactions, and more. In short, this was the complete aircraft design experience. The University of Washington’s program is also notable for its industry participation. Local companies like Boeing, Aeronautical Testing Service (ATS), Fiberlay, the University’s low speed Kirsten Wind Tunnel, and local model airplane experts participate and donate materials, funds, time and guidance. CFD in Early Design Phase The focus of this article is the CFD analysis that was conducted as part of the early design phase. One of the challenges of the CFD team was to learn the basics of CFD and how to use STAR-CCM+ to perform a thorough computational analysis, providing inputs for the initial design and eventually improving it. The fact that STAR-CCM+ is both easy-to-use and has many automation capabilities ensured bottlenecks in the simulation process were easily avoided. STAR-CCM+ was used for a series of planform studies, initially to find the base planform design that would be extensively tested in the wind tunnel. In total, 34 different configurations were analyzed from a total of 274 CFD runs for 300 total man hours

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p ABOVE Initial planform designs studied

p ABOVE STAR-CCM+ results for CM vs alpha

..::FEATURE ARTICLE Aerospace

ABOVE Polyhedral mesh on full model of aircraft

Why Study A&A at the UW? The Aerospace Engineering industry is at the forefront of revolutionary technological developments in transportation, exploration, and national security, with new and significant challenges emerging every day. The Department of Aeronautics and Astronautics at the University of Washington wants to help meet those challenges by offering bachelor’s, master’s and doctoral degrees that prepare students to become leaders in this exciting field. Our program is at the forefront of current research in space-based information systems, energetics, complex autonomous systems, composite materials, and more, ensuring our graduates will be competitive in academics and industry well into the future.

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..::FEATURE ARTICLE Aerospace

ABOVE Cd vs alpha in the final cruise configuration - Comparison of STAR-CCM+ (CFD Cruise) and wind-tunnel (WT Cruise) results

p ABOVE Streamlines behind the wings

ABOVE Cl vs alpha for the V-Tail configuration - Comparison of STAR-CCM+ (CFD) and wind-tunnel (WT) results

ABOVE Cm vs alpha in the final cruise configuration - Comparison of STAR-CCM+ (CFD Cruise) and wind-tunnel (WT Cruise) results

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and 22,500 computing hours. These are impressive numbers! All CFD simulations were conducted on a 96 core Linux cluster at ATS. STAR-CCM+, CD-adapco’s finite volume based solver, was used for simulating fluid dynamics and to provide realistic inputs to the design of the final model. Half and full model cases were run after the preliminary planform studies to select the final configuration. Detailed simulations were then run to design the engine nacelle. Design Study Three of the initial planform designs are shown (previous page), with the plate representing the trunnion plate of the 2009 University of Washington’s Capstone UAV wind tunnel model, which was to be used as a base for the planform design. The wing names refer to the sweep angles of the inboard and outboard leading edges, respectively. STAR-CCM+ has been extensively validated for external aerodynamics and that confidence in the code translated to initial design studies being conducted solely in CFD. A polyhedral mesh was created for the half & full models with nearly 1.3 million and 4 million cells, respectively. The k-є turbulence model was used. Of all configurations studied, the 56-40 planform was chosen for further study in the wind tunnel. The CFD results (accompanying images) showed that the 56-40 configuration had a pitch-up problem from 6 to 15 degrees of angle of attack due to outboard wing stalling. To eliminate the pitch-up problem, two different configuration modifications were studied, the first involving adding a chine and the second using a dogtooth wing. Although the addition of a chine was theoretically expected to remove the pitch-up problem, results from STAR-CCM+ showed that the chine created a vortex and outboard wing separation at 12 degrees angle of attack. At 20 degrees, the entire outboard wing had stalled and parts of the inboard wing showed separation too. A dogtooth wing was attempted next with the dogtooth sized to 7% of the wing chord. This design showed improvements in pitching and lift over the base case but still didn’t solve the pitch-up problem. Eventually, this was left for wind tunnel tests. The image opposite (middle) shows the CFD results for the 2010 base case, 2010 V-Tail planform and the 2009 wind tunnel data for the 2009 V-Tail configuration. The final tail design for the 2010 UAV included horizontal and vertical tails. Nearly 25 different configurations were simulated in

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..::FEATURE ARTICLE Aerospace

p ABOVE + BELOW Streamlines from STAR-CCM+ showing aircraft with Chine at different angles of attack

CFD to optimize the initial wind tunnel model. After the wind tunnel tests were completed, the final configuration was simulated once again using STAR-CCM+. The results of this verification simulation showed excellent comparison with wind tunnel data over a wide range of angles of attack as seen in the adjoining graph. The cruise conditions of the aircraft were well captured by CFD. Finally, the effect of wind tunnel walls was also simulated in STAR-CCM+ to allow comparison of wind tunnel and free flight characteristics. One of the most important lessons learned from the Capstone project was that CFD and Wind Tunnel Testing are integral parts of the design cycle and are complementary to each other. Alex Lacomb, CFD Lead for the program, said,

“STAR-CCM+ has the easiest GUI I’ve experienced in a CFD code, in addition to the easy automated meshing which made the tool very valuable to the design team.” The aircraft was successfully flight tested last summer and bears testimony to the excellent work of the students at the University of Washington’s Department of Aeronautics & Astronautics. CD-adapco is proud to be associated with such a rewarding research program for undergraduate students. <

What we couldn’t do in previous years of the program with other codes was made possible with STAR-CCM+. We were able to run hundreds of high-end CFD analyses in 4-5 weeks by a group of seniors who before that had had no experience with commercial CFD.

i MORE INFORMATION ON THE UNIVERSITY OF WASHINGTON’S ACADEMIC AEROSPACE PROGRAMS: www.aa.washington.edu/

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..::FEATURE ARTICLE Oil & Gas

BELOW Cooldown analysis of a subsea Christmas tree

Integration of 1D & 3D Flow Simulation Helps Meet Deepwater Flow Assurance Challenges Deborah Eppel - CD-adapco

While 1D flow simulation software can accurately and rapidly simulate simple tasks, such as long straight runs, they are not adapted to complex 3D geometries such as separators, slug catchers and dry trees. Full 3D Computational Fluid Dynamics (CFD) codes, on the other hand, have the proven ability to accurately predict flow in these situations, although typically at a much higher computational cost. Generating combined 1D/3D simulations promises the best of both worlds: by making it possible to simulate complex systems of piping and equipment at a much higher level of accuracy than 1D-only simulations and in much less time than 3D-only codes, problems can be prevented earlier in the design stage. Challenges of deepwater drilling and production As the amount of oil and gas that can easily be produced has declined, exploration and production companies have turned towards less accessible hydrocarbon sources including deepwater and ultra deepwater basins. However, the challenges associated with extracting oil and gas from such environments are considerable. To cite but a few: water depth reaching 3000 meters and beyond, higher pressures of both well fluids and ocean bottom water, high temperatures of well fluids that can run up to 300oF/150oC in near-freezing ocean water, much longer runs of piping and risers back to production facilities and tricky ocean currents in deeper water. These difficult conditions can lead to flow assurance problems such as slugging and the formation of hydrates and waxy paraffins in an environment where remediation is far more expensive and time-consuming than in normal offshore conditions.

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Advantages and limitations of 1D simulation tools Flow assurance analysts typically use 1D modeling tools for an overall view of a field’s production scheme. 1D simulation is used for sizing well tubing, flow lines, and receiving facilities in order to maximize the initial production while avoiding excess slugging and liquid surges later in the life of the field. Multiphase flow simulation of the well and pipeline network with a 1D code such as OLGA addresses thermal insulation and arrival temperature requirements as well as liquid inventories, flow patterns, and potential for instabilities in production systems. In order to provide usable run times, 1D simulation has traditionally reduced 3D multiphase flow to a simplified 1D component. This requires estimating the flow regime – for example stratified, annular or plug – historically accomplished by conducting expensive physical experiments to provide the 1D flow coefficients. The accuracy of the 1D simulation is thus limited by the physical conditions in which g

RIGHT Polyhedral mesh of a subsea Christmas tree

Flow Assurance is the ability to identify and prevent potential fluid related problems from impacting oil & gas production throughout the asset life.

..::FEATUREâ&#x20AC;&#x2C6;ARTICLE Oil & Gas

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..::FEATURE ARTICLE Oil & Gas

p ABOVE Amalysis of a Y junction with two valves

$140

$100

NOMINAL REAL

$50

average Brent spot priCES

$0 MAY ‘87 JUNE ‘90

JAN ‘99

JAN ‘05

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JAN ‘08

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JAN ‘11

Energy Information Administration and Bureau of Labor Statistics

..::FEATURE ARTICLE Oil & Gas

p ABOVE Flow streamlines around an oil rig

the experiment was performed; as the oil and gas industry moves to increasing depths, experiments performed at shallower depths become less and less relevant. Another concern is that the geometries of deepwater equipment often surpass the level of complexity that can be simulated using “off-the-shelf” components provided in 1D simulation tools. Situations where the pipeline changes direction, meets up with another pipeline, or flows into a resevoir all represent inherent 3D problems. There are many others. Even in long 1D pipes, flow conditions may arise, such as recirculating flow in risers, that go beyond 1D’s predictive capabilities. In another example, gas lift is sometimes used by pumping pressurized gas through the pipe to push the water forward and prevent slugging, another inherently 3D phenomena that cannot be easily modeled with 1D codes. Increasing need for 3D simulation 3D simulation can address these issues thanks to its ability to simulate multiphase flow in a 3D environment with no need for assumptions based on empirical data. A CFD simulation provides fluid velocity, pressure, temperature, gas composition, and other variables throughout the solution domain for problems with complex geometries and boundary conditions. As part of the analysis, an engineer may change the geometry of the system or the boundary conditions and observe the effect of these changes on fluid flow patterns or distributions of other variables, such as gas composition. CFD is becoming increasingly important in the deepwater environment because engineers often have no empirical data to guide them. Several obstacles, however, have prevented engineers from taking greater advantage of CFD. For example, CFD simulations for the complex geometries found in subsea drilling and production can be computationally expensive and used to take an unacceptably long period of time to solve. However, improvements in solution algorithms and the move towards massively parallel high performance computing configurations have overcome this obstacle. Another potential obstacle is that engineers want to use CFD to simulate complex subsea equipment, but want to continue handling simple geometries such as straight pipeline runs with

faster 1D codes. However, with the 1D and 3D software each simulating specific sections of the fluid flow, each code becomes dependent upon the other for information such as flow velocities, flow rates, and pressures at the boundaries between 1D and 3D simulated components. In the past, this required a cumbersome process whereby the analyst moved data back and forth between 1D and 3D simulations. The analyst would first simulate the entire system in 1D while knowing that accuracy would suffer in those areas where the geometry is complex. Next, the analyst would extract flow conditions at the boundaries of the geometrically complex areas and use them as the boundary conditions for the 3D simulation. The 3D simulation would provide much greater clarity into what is happening in the complex areas. These changes would of course affect the 1D environment and the 3D results would need to be re-entered into the 1D simulation which would be re-run. Depending on the stage in the design process and the level of accuracy needed, several more iterations of manually exchanging boundary conditions between the 1D and 3D simulations might be needed. All of these iterations would have to be repeated for every design change or new set of operating conditions. Seamless integration between 1D and 3D simulation The recent automation of information exchange between 1D and 3D codes greatly reduces the time required to perform this type of analysis while improving the accuracy of the results by providing seamless flow of information between the two. The most prominent example is the integration of STAR-CCM+ with OLGA, a leading 1D code. The STAR-CCM+ user can run OLGA as a slave process which causes the two codes to exchange data at each time step, much more frequently than is possible using manual methods. In a typical example, a long pipeline was modeled using OLGA while STAR-CCM+ was used to simulate the multiphase transient characteristics of the slug catcher at different flow rates and gas/liquid ratios. The analysis enabled engineers to successfully optimize the design of the slug catcher to handle the wide range of flow conditions throughout the asset life, thereby greatly reducing the risk of having to replace it at a potential cost of tens of millions of dollars.<

i MORE INFORMATION ON THE OIL AND GAS INDUSTRY: www.cd-adapco.com/industries/energy

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..::FEATURE ARTICLE Marine

Chasing The Wind The New State-of-the-Art in the America’s Cup Design

ABOVE Wave pattern at 11 knots

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..::FEATURE ARTICLE Marine

Read about how our software is used in the Marine industry:

www.cd-adapco.com/industries/marine

Dr. Ignazio Maria Viola, School of Marine Science and Technology, Newcastle University, and Dr. Raffaele Ponzini, CILEA

The America’s Cup is the oldest trophy in the world and the competing platform for the most advanced technologies in the marine field. In recent years, CFD has become the most powerful tool for both aero and hydrodynamic design. A research project steered by Dr. Ignazio Maria Viola shows how CFD can be applied to the design of an America’s Cup yacht.

The America’s Cup was sailed for the first time in 1851 at Cowes, Island of Wight, in conjunction with the largest exhibition ever held until then: the Prince Albert’s Great London Exhibition. The Americans took the opportunity to show their advanced knowledge of naval architecture and built the schooner America for the event. America was definitively faster than the 14 other competing British yachts and won the “100 Guinea Cup,” which was subsequently renamed the America’s Cup. The Cup was then donated to the New York Yacht Club as a token of their enthusiasm for taking part in international challenges. For the following 132 years and 24 contests, the Americans remained the undefeated holders of what they now affectionately called “the Auld Mug.” Since 1983, however, the Cup has been successively won by Australia, USA, New Zealand and Switzerland, before finally being brought back to the USA in 2010 with the San Francisco

Yacht Club’s victory of the 33rd America’s Cup. Today, the America’s Cup is the oldest trophy in the world and the most expensive to win. Each challenger spends tens of millions of dollars in designing, building, and sailing its boat, which represents the state-of-the-art of the worldwide marine industry. Wind tunnel tests, towing tank tests and Computational Fluid Dynamics (CFD) are the main tools used in the design of an America’s Cup yacht. However, while ten years ago experimental investigations were much more important than numerical analysis, nowadays the situation is reversed. The ongoing growth of computational capabilities is increasing the usage of CFD even further. Commercial codes are becoming easier to use and allow more and more complex physics to be modeled and simulated accurately. For instance, the laminar separation bubble on the leeward side of the sails (which is followed by the laminar-to-turbulent transition, reattachment and, finally, trailing g

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..::FEATURE ARTICLE Marine

RIGHT Simulated breaking bow wave

The America Crafted on commison by the New York Yacht club to compete against British sailboats (an intense rivalry), it was to sail the first inaugural yacht race around the Isle of Wight in 1851, an event launched by Prince Albert to promote friendly competition between nations. The ‘America’ (pictured above) won the competition so convincingly that the race was named after it. The Times reported: “off Cowes were innumerable yachts and on every side was heard the hail is the America first?” The answer, “yes”; “What is second?” The reply - “nothing.” In the telling and re-telling of this, many believe that it was Queen Victoria who posed the question and it was a signalman who replied, “Ma’am, there is no second.” The phrase is now part of America’s Cup lore. So the cup won by America, became the America’s Cup. In 1857, the owners presented the trophy to the New York Yacht Club as a perpetual “challenge cup for friendly competition between foreign countries.” www.americascup.com

edge separation), the transition on the keel and the rudder, or the dynamic behavior of yachts in waves, are all physics that can be modeled by CFD codes such as STAR-CCM+. Such numerical codes have also become more reliable and accurate. Ten years ago, the difference between numerical and measured drag for a bare hull was of the order of 10%, while in this project, it was found to be of the order of 1% for a hull with its appendages. The increase in accuracy has allowed CFD to be used as a reliable design and analysis tool. However, as with every very powerful tool, CFD must be managed very carefully. Wrong conclusions can easily be reached, thereby requiring the results to be validated against high quality experimental data. In particular, a well set-up CFD analysis has to prove its ability to predict the experimental results without knowing them beforehand. In a recent research project [1] carried out in the Yacht Research Unit of the University of Auckland (New Zealand) and coordinated by Dr. Ignazio Maria Viola, two candidate hulls (monohulls) designed for the 32nd America’s Cup were tested in a towing tank and analyzed with STAR-CCM+. Only the towing tank data of the first of the two hulls was known when the CFD analysis was performed. The measured sink, trim, and resistance of the second hull were predicted by STAR-CCM+ without prior knowledge of experimental data. The hulls were modeled with the keel and the rudder, which significantly affected the resulting pitching moment. The longitudinal trim had to be computed very accurately to predict the resistance correctly. The figures show the very close agreement between the computational and experimental results. In particular, the relative trim at different boat speeds was computed within an accuracy of the order of 0.01°, translating into an accuracy in the resistance predictions of the order of 1% – which, very interestingly, happens to be the same order of magnitude as the uncertainty of the experimental tests! This high level of accuracy could be achieved thanks to the efforts of CD-adapco in developing a reliable and accurate tool for the marine industry: “STAR-CCM+ is the most advanced existing code to compute hull performance and it represents the state-of-the-art for the America’s Cup community,” said Dr. Viola. The computation was run on a simple multi-core workstation. The hulls were modeled with about 2 million cells. The 6-DOF module was used to model the free to sink and trim condition. When the grid and numerical set-up were validated against experimental data, the hull dynamic behavior in waves was also modeled.

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The next America’s Cup will be sailed in much rougher conditions than what we have been used to so far and sea-keeping will be fundamental for a successful design. The yachts will be required to sail in 30 knots of wind, thereby reaching very high speeds in downwind conditions. This results in new questions being raised: will we be able to perform experimental tests within the necessary accuracy to validate CFD’s predictions? How will we measure differences in the hydrodynamic drag smaller than 1% in the towing tank when we have to model 20-plus-knots of boat speed in waves caused by a 30-knot wind? The challenge is open. The only certainty so far is that these conditions will not be a problem for the engineering simulation software STAR-CCM+. <

REFERENCES: [1] Viola I.M., Flay R.G.J., Ponzini R., CFD Analysis of the Hydrodynamic Performance of Two Candidate America’s Cup AC33 Hulls, International Journal of Small Craft Technology, Trans. RINA, in press.

..::FEATURE ARTICLE Marine

ABOVE The two 1/4th model-scale America’s Cup yachts (IACC-V5 class)

ABOVE Vertical height of the wave pattern at 11 knots for the full-scale model

LEFT Pressure coefficient subtracted from hydrostatic pressure

ABOVE Numerical and experimental resistance versus Froude number (boat speeds from 6 to 12 knots full scale)

ABOVE Numerical and experimental trim versus Froude number (boat speeds from 6 to 12 knots full scale)

ABOVE Numerical and experimental sink versus Froude number (boat speeds from 6 to 12 knots full scale)

i FOR MORE INFORMATION ON THE AMERICA’S CUP PLEASE VISIT: www.americascup.com

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dr. mesh

..::FEATURE ARTICLE Dr. Mesh

The acclaimed return of Dr. Mesh

how to: insert a 3D STAR-CCM+ scene in a Microsoft PowerPoint presentation After a long sabbatical in my JAVA™ Hut cultivating macros, I’ve decided that it’s time I returned to my true vocation: sharing my incredible knowledge of meshing and post-processing in the pages of Dynamics magazine. (Although to be honest, I’d long since exhausted my supplies of SPF60 sunscreen, tropical-grade insect repellent and surgical strength gin.) For today’s tropic, I mean topic, I have a very exciting subject in mind. Easy, but “oh-so-useful!” I am going to give you a step-by-step explanation of how to insert a 3D STAR-CCM+ scene into a PowerPoint presentation. Bringing your scenes to life will help show your boss/colleagues/customers the phenomenon that you have just pinpointed in all its 3D glory, while undoubtedly enhancing the quality of your presentations.

STEP 1: Download and install STAR-View+. STAR-View+ is a free, 3D interactive results viewer for STAR-CCM+ which allows the user – whether he/she has a STAR-CCM+ license or not – to “see” a STAR-CCM+ scene in the same way as the engineer who created it. It is possible to zoom, pan and rotate the CAE stored model and post-processing data as well as show and hide features within the scene. When installing STAR-View+, make sure that you select the option “Install STAR-View+ Office Add-In.”

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..::FEATURE ARTICLE Dr. Mesh NB: follow the same

Right-click here

steps in Microsoft Word if you wish to insert a scene into a text document.

... or there

2 STEP 2: Export the 3D scene that you want to share.

STEP 5: Save your presentation. Save the presentation as a “PowerPoint Macro-Enabled Presentation.”

In STAR-CCM+, right-click on the scene you want to save or on the name of the scene in the Scene/Plot tree and select the option “Export 3D Visualization File.”

New “CD-adapco” tab

STEP 3: Launch Microsoft PowerPoint.

Until next time...

Right-click on the scene to reset it to its original view STEP 6: Slide show your presentation!

You will notice a new tab called “CD-adapco” has been added.

Now, you can interactively translate and rotate the scene to expose its different angles. Please note actions such as zooming or hiding/showing parts are not yet available when using STAR-View+ in Microsoft PowerPoint.

Bring your results to life with the new, free, 3D interactive results viewer for STAR-CCM+

STEP 4: Insert the scene. Click on “Insert a Scene” in the “CD-adapco” ribbon and select the scene of interest.

STAR-CCM+ provides a free, stand-alone results viewer, STAR-View+ that facilitates collaboration between engineering teams by giving everyone access to interactive visualization of the computed results. STAR-CCM+ allows users to distribute post-processed simulation results as “scene files” containing a three-dimensional representation of the stored CAE plot. When viewed using STAR-View+, scene files allow the viewer to zoom, pan, and rotate the stored model and post-processing data as well as show and hide features within the scene. Now anyone, whether a STAR-CCM+ user or not, can have the luxury of fully exploring the solution. STAR-View+ is free to distribute and requires no license, which means that you can simply attach it to an e-mail with a selection of scene files. Free download at: http://www.cd-adapco.com/downloads/star_view_plus/download.html

i SEND ME YOUR THOUGHTS & SUGGESTIONS FOR FUTURE DR. MESH ARTICLES: dr.mesh@cd-adapco.com

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..::REGULARS Training Training to fit into your schedule & your location:

www.cd-adapco.com/training

TRAINING VENUES Detroit, United States Houston, United States Seattle, United States London, United Kingdom Nuremberg, Germany Paris, France Turin, Italy Bangalore, India

Choose from the following courses: • JAVA™ Scripting - Process Automation • STAR-CCM+ Wizard Creation • Virtual Tow Tank • Rigid Body Motion • Vehicle Thermal Management (Incl. braking system analysis) • Effective Heat Transfer • Virtual Reliability Laboratory (Component Thermal Analysis) • Computational Methods for Nuclear Engineering

• Advanced Engineering Optimization (Coming Soon) • Internal Combustion Engine Analysis course • Turbomachinery Engineering (Coming Soon) • Applied Computational Combustion • External vehicle aerodynamics (incompressible) (Coming Soon) • Aeroacoustics • High Speed Aerodynamics (Coming Soon) • Energy Balancing for Buildings (Coming Soon)

• Fluid Dynamics for Biomedical Industry (Coming Soon) • Offshore Computational Engineering • Battery Modeling • Casting (Coming Soon) • Cabin Comfort Analysis (Thermal, Acoustic, HVAC systems) • Fluid & Thermal Analysis for the Electronics Industry • Computational Analysis of Wind Parks • Wind Turbine Analysis (Coming Soon)

Training Courses Training adds incredible value to the software you have purchased and comes highly recommended by all. Courses are regularly held at CD-adapco offices around the world including: Detroit, Houston, Seattle, London, Nuremberg, Paris, Turin and others. The courses listed on our website can be scheduled to suit your requirements. To take advantage of this, please request information from your local training administrator. Courses are held in small groups and the number of available places can be checked online at: www.cd-adapco.com/training/multi_day.html Just click on the course you are interested in to get an overview on the dates, locations, and availability. If the course of your choice isn’t scheduled in an office near you, then why not take it via Distant Learning, CD-adapco’s new internet based remote learning service. To find out more or to get a course scheduled to suit your requirements please contact your local training administrator.

View your local course offerings, customer testimonials and register for an upcoming course at: www.cd-adapco.com/training To Register for a Course: Complete the online registration: www.cd-adapco.com/training Or request a faxable form from your training administrator:

USA:

UK: training@cd-adapco.com

(+44) 020 7471 6200

Germany: training@cd-adapco.com

(+49) 911 946433

France: training@cd-adapco.com

(+33) 141 837560

Italy:

(+39) 011 562 2194

training@cd-adapco.com training@cd-adapco.com

(+1)

734 453 2100

Specialized Courses: New specialized courses relating to application specific areas are developed throughout the year. Check for these courses at: www.cd-adapco.com/training

STAR-Tutor Interactive / STAR-Tutor On Demand: STAR-Tutor Interactive offers a broad range of tutorial and elective short courses which are delivered by our highly qualified support team via live streaming internet feed. These virtual classes extend and focus knowledge built up from the Introductory STAR-CCM+ class to cover specific engineering analysis areas. For more information, please visit: www.cd-adapco.com/training/star_tutor.html STAR-Tutor On Demand is a self-paced introductory training to the STAR-CCM+ process. Using a pre-recorded video of a support engengineer, STAR-Tutor On Demand offers engineers the ability to view a complete STAR-CCM+ analysis from CAD import to post-processing in a single one hour session. For more information, please visit: www.cd-adapco.com/training/on_demand.html

Note: In most situations it will be possible to register trainees on the course of their choice. However, if requests for places on courses are received too close to the course date, this may not be possible. Availability of places can be obtained online or by contacting your local office.

i CHECK OUT THIS LINK FOR COURSE AVAILABILITY: www.cd-adapco.com/training/calendar

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..::REGULARS Events Browse our workshops, conferences + webinars

www.cd-adapco.com/events

MARCH 19-21 + FREE TRAINING! STAR-CCM+ ORIENTATION (ATTENDEES ONLY) Grand Hotel Huis ter Duin • Noordwijk • Netherlands The first ever STAR Global Conference will be held in March 2012 in the Netherlands. Join engineers from around the world and explore the technology and techniques that will revolutionize your CAE process and empower you and your organization to successfully achieve your objectives.

Events

CD-adapco regularly participates in many global trade shows. To get the chance to talk in person with our experienced and friendly representatives, please make a note of our appearances at the confirmed shows below. For more information please contact our events staff: North America: Tara Firenze - tara.firenze@cd-adapco.com Europe: Sandra Maureder - sandra.maureder@cd-adapco.com North America AIAA Aerospace Sciences January 9-12, 2012 Nashville, TN AABC 2012 February 6-10, 2012 Orlando, FL ASNE Day 2012 February 9-10, 2012 Arlington, VA SolidWorks World 2012 February 12-15, 2012 San Diego, CA Renewable Energy World Conference & Exhibition 2012 February 14-16, 2012 Long Beach, CA 2012 SAE Hybrid & Electric Vehicle Technology Display February 21-23, 2012 San Diego, CA SAE 2012 World Congress April 24-26, 2012 Detroit, MI AHS International 68th Annual Forum and Technology Display May 1-3, 2012 Fort Worth, TX OTC 2012 May 1-3, 2012 Houston, TX 2012 ASEE Annual Conference & Exposition June 10-13, 2012 San Antonio, TX AUVSI’s Unmanned Systems North America 2012 August 7-10, 2012 Las Vegas, NV

i FOR MORE INFORMATION ON OUR EVENTS:

Battery Power 2012 September 18-19, 2012 Orlando, FL SPE Annual Technical Conference and Exhibition 2012 October 8-10, 2012 San Antonio, TX

Europe WEAF Annual Conference 2012 February 22, 2012 Winter Garden, UK 12th Stuttgart International Symposium 2012 March 13-14, 2012 Stuttgart, Germany STAR GLOBAL CONFERENCE 2012 March 19-21, 2012 Amsterdam, Netherlands 8th International Fluid Power Conference IFK 2012 March 26-28, 2012 Dresden, Germany EWEA 2012 April 16-19, 2012 Copenhagen, Denmark COMPIT 2012 April 16-18, 2012 Luettich, Belgium 1st NAFEMS DACH Regional Conference May 8-9, 2012 Bamberg, Germany All Energy 2012 May 23-24, 2012 Aberdeen, UK

Power Gen Europe 2012 June 12-14, 2012 Cologne, Germany ASME Turbo Expo 2012 June 12-14, 2012 Copenhagen, Denmark AABC Europe 2012 June 18-22, 2012 Mainz, Germany ACHEMA 2012 June 18-22, 2012 Frankfurt, Germany 2012 RAeS Applied Aerodynamics Conference July 17-19, 2012 Bristol, UK ONS 2012 August 28-31, 2012 Stavanger, Norway SMM 2012 September 4-7, 2012 Hamburg, Germany Euromech 2012 - EFMC9 September 9-13, 2012 Rome, Italy

www.cd-adapco.com/events

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• STAR-CCM+ • STAR-CD • Engineering Services • Dedicated Support

Simulation Software for a New Frontier in Engineering Innovation Follow us online. For more information: info@cd-adapco.com www.cd-adapco.com