INTERNATIONAL JOURNAL FOR TRENDS IN ENGINEERING & TECHNOLOGY VOLUME 5 ISSUE 2 – MAY 2015 - ISSN: 2349 - 9303
Design and Analysis of Turbine Blades in a Micro Gas Turbine Engine Lakshmy Devi.S.M Aeronautical Engineering Department, PMC Tech, Tamil Nadu lakshmysm@gmail.com Abstract— This paper is based on the design and analysis of turbine blades in a micro gas turbine engine. Micro-gas turbine engines offer advantages over the other technologies for small-scale power generation. A combustor is the heart of any engine; where in the micro gas turbine, it should be compact, simple, inexpensive and robust in construction. The burned gases from the combustor pass through the turbine blades. The designing and manufacturing of the turbine blades are very difficult when the blade angle, blade size and shape are considered. The design of the turbine blade passages is broadly based on aerodynamic considerations and it is to obtain optimum efficiency, compatibility with compressor and combustor design. For this, the specifications of many micro gas turbine engines are taken by conducting a literature survey to get the design data for an apt turbine blade. By these values, the flow parameters of the engine are obtained and are taken for analyzing purposes to get increased momentum thrust. Here, the design is done by using the software CATIA and it is then exported to FLUENT for analyzing. The result shows that the estimated design and performance is achieved. Index Terms — Blade angle, CATIA, FLUENT, Micro Gas Turbine engine, Turbine blades. —————————— ——————————
1 INTRODUCTION An engine or motor is a machine designed to convert energy into useful mechanical motion. A gas turbine is a rotary engine that extracts energy from a flow of combustion gas. It has an upstream compressor coupled to a downstream turbine, and a combustion chamber in-between. Energy is added to the gas stream in the combustor, where fuel is mixed with air and ignited. In the high pressure environment of the combustor, combustion of the fuel increases the temperature. The products of the combustion are forced into the turbine section. There, the high velocity and volume of the gas flow is directed through a nozzle over the turbine blades, spinning the turbine, which powers the compressor and drives the mechanical output for some turbines. The energy given up to the turbine comes from the reduction in the temperature and pressure of the exhaust gas.
Micro turbines are becoming widespread for distributed power and combined heat and power applications. They are one of the most promising technologies for powering hybrid electric vehicles. They range from hand held units producing less than a kilowatt, to commercial sized systems that produce tens or hundreds of kilowatts. Basic principles of micro turbine are based on micro combustion.
2 THEORETICAL CALCULATION FOR ENGINE DESIGN By using isentropic relations and Area-Mach number relation, calculations of the engine parameters are done. Table 1: ENGINE PARAMETERS
Fig 1: MGT
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Mach
Pressure (bar)
0.56 0.51 0.185 0.277 0.409 0.709
1.01325 1.253 4 3.91 1.024 0.917
Temper ature (K) 288.16 306.31 427.06 873 626.09 609.27
Density (kg/m3) 1.225 1.052 3.26 1.56 0.569 0.524
Area ×10 -3 (m2) 1.328 1.646 1.24 1.24 2.72 1.73
Velocity (m/s) 190.55 179.01 76.68 160.24 200.27 341.91
INTERNATIONAL JOURNAL FOR TRENDS IN ENGINEERING & TECHNOLOGY VOLUME 5 ISSUE 2 – MAY 2015 - ISSN: 2349 - 9303 3 LITERATURE SURVEY
Fig 2: GRAPHICAL COMPARISONS OF ENGINE SPECIFICATIONS
This is done for finding the specifications like length, diameter, mass, fuel, mass flow rate etc of micro gas turbine engines designed by many different industries.
From the above graphical comparisons, the new engine parameters found out are as follows,
1. Mass of the engine
= 2050g
2.
Maximum rpm
= 120,000
3.
Mass Flow rate
= 310 g/sec
4.
Fuel consumption
= 445g/min
5.
Pressure Ratio
= 3.2 : 1
6.
Diameter of the engine = 120 mm
7.
Length of the engine
= 265 mm
8.
Thrust of the engine
= 166.42 N
4 GEOMETRIC DESIGN PROCESS
Fig 3: ENGINE LAYOUT
5
BLADE PARAMETERS 1. Blade span
= 80.00 mm
2. Blade spacing
= 27.92 mm
3. True chord
= 38.667 mm
4. Stagger angle
= 38.80 degrees
5. Aspect ratio
= 2.07
6. Axial chord
= 30.14
7. Leading edge metal angle = 11 degree
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INTERNATIONAL JOURNAL FOR TRENDS IN ENGINEERING & TECHNOLOGY VOLUME 5 ISSUE 2 – MAY 2015 - ISSN: 2349 - 9303 8. Trailing edge metal angle = 0, 30, 45 degree
angles of attacks.
9. Leading edge radius
7 RESULTS AND DISCUSSION
= 5.00 mm
Fig 6: CONTOUR OF PRESSURE MAGNITUDE AT 0 ANGLE OF ATTACK
Fig 4: BLADE GEOMETRY
Fig 5: MESHED VOLUME Fig 7: CONTOUR OF VELOCITY MAGNITUDE AT 0 ANGLE OF ATTACK
6 NUMERICAL ANALYSIS FINITE ELEMENT METHOD After the mesh has been exported to Fluent, we have to set the parameters before running the design. This is a 3D analysis and this should be mentioned at the starting of Fluent. Then the grid has to be checked and scaled in order to make sure the mesh was well built. On the energy equation, the laminar flow to be set is default one. Keep the density as constant and set the velocity and temperature in boundary conditions, obviously these values change from one design to another. Before running the analysis the model has to be initialized from the boundary conditions inlet. And finally the design is ready to iterate. After the solution gets converged, the values of velocity and pressure are taken at different
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Fig 8: CONTOUR OF PRESSURE MAGNITUDE AT 30 ANGLE OF ATTACK
INTERNATIONAL JOURNAL FOR TRENDS IN ENGINEERING & TECHNOLOGY VOLUME 5 ISSUE 2 – MAY 2015 - ISSN: 2349 - 9303 8 CONCLUSION From designed and analyzed results, increased thrust has been achieved successfully by taking velocity and pressure at different angles of attacks. Lighter in weight, less cost, less pollution and bio-fuel usage are some of the advantages of micro gas turbine engines.
9 FUTURE WORK The future work directs towards the designing and analysis of a Nozzle plate with types of holes by replacing Nozzle Guide Vanes at the exit of Combustion Chamber, to reduce the blade designing complications. ACKNOWLEDGMENT Fig 9: CONTOUR OF VELOCITY MAGNITUDE AT 30 ANGLE OF ATTACK
I wish to thank my Head of the Department and guide for their constant source of inspiration to this project. REFERENCES
Fig 10: CONTOUR OF PRESSURE MAGNITUDE AT 45 ANGLE OF ATTACK
[1] T. Witkowski, S. White, C. Ortiz Duenas, P. Strykowski, T. Simon, “Characterizing the Performance of the Sr-30 Turbojet Engine”, University of Minnesota [2] J. Peirs, F. Verplaetsen, D. Reynaerts, “A Micro Gas Turbine Unit for Electric Power Generation: Design And Testing Of Turbine And Compressor”, Katholieke Universiteit Leuven, Department of Mechanical Engineering, Belgium [3] R. Tuccillo and M.C. Cameretti , “Combustion and Combustors for MGT Applications” Dipartimento di Ingegneria Meccanica per l’Energetica (D.I.M.E.) [4] Alan H. Epstein, “Millimeter-Scale, Mems Gas Turbine Engines”, Massachusetts Institute of Technology [5] Dr:S.A.Channwala and Dr.Digvijay Kulshreshtha, "Numerical simulation approach and design optimization for micro combustion chambers” [6] Stephen Lynch, “Flow and Thermal Performance of a Gas Turbine Nozzle Guide Vane with a Leading Edge Fillet” [7] J.C.Bruno, A.Coronas, “Power quality and air emission tests in a MGT cogeneration plant”, Spain [8] Hill Philip,Pearson Carl, “Mechanics and Thermodynamics of Propulsion”, second Edn., Addison Wesly,1992. AUTHOR PROFILE:
Lakshmy Devi.S.M is currently pursuing masters degree program in aeronautical engineering in PMC Tech, Tamil Nadu, India, PH-08089791859. E-mail: lakshmysm@gmail.com Fig 11: CONTOUR OF VELOCITY MAGNITUDE AT 45 ANGLE OF ATTACK
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