Aerodynamic Characteristics of Sedan with the Rolling Road Ground Effect Simulation System

Page 1

Vehicle Engineering (VE) Volume 2, 2014

www.seipub.org/ve

Aerodynamic Characteristics of Sedan with the Rolling Road Ground Effect Simulation System Yingchao Zhang1, Linlin Ren1, Kecheng Pan2, Zhe Zhang*1 State Key Laboratory of Automotive Simulation and Control, Jilin University, Changchun 130012, China

1

China FAW group corporation R&D center, Changchun 130012, China

2

zhangzhejlu@jlu.edu.cn

*

Abstract The rolling road ground effect simulation system is one of the key factors affecting the accuracy and reliability of automotive wind tunnel test. It is necessary for wind tunnel experiments to reduce the influence of ground boundary layer effect in wind tunnel. In this paper, several CFD simulations were carried out to investigate the turbulence airflow and its differences with the wheel-rotation and the under-hood flow field. And the car model is one productive car model designed by Audi. It simulated the different flow field of automotive wind tunnel with or without ground effect rolling road system respectively based on Star - CCM+ CFD code. These works focus on the following three parts: first is setting up monitoring points in different positions of flow field, second is monitoring their velocity through vector and streamlines, and third is analyzing the two cases by comparing them. Rolling road system with belt width bigger than car width has great effect on accelerating the air velocity near the ground at the bottom of the model to control the ground boundary layer development around model. In the flow field behind the model, using the rolling road system with wide belt is a wise choice to reduce the velocity of the wake flow near the ground. Keywords Automotive Wind Tunnel; CFD; Aerodynamics of Road Vehicle; Ground Effect

Introduction As one of the most important features on automobile, automotive aerodynamic characteristic has a close relationship with the related characteristics of the internal and external flow field near the automobile. Automotive wind tunnel is the main test site, in which we analyze and verify the aerodynamic theory and the

corresponding parameters in experimental study, so a lot of important conclusions on automotive aerodynamics are derived from it. Nowadays there are many tunnels in use around the world, so Jilin University’s building its own automotive wind tunnel is a substantial beginning of automotive wind tunnel test theory and technology development in China. Jilin University wind tunnel adopted the widely used rolling road system with belt to reduce the ground effect in wind tunnel test. In wind tunnel test, there are boundary layers near the test ground in flow field, which does not tally with the actual driving conditions, and will reduce the reliability of results. The above phenomenons are named as ground effect of Wind tunnel test. Many studies have shown that too thick boundary layer is to be generated near test ground due to the ground effect of Wind tunnel test, which will directly influence the measuring results of six-component force in wind tunnel test and reduce the measured drag coefficient of the car. In this paper, in order to supplement the domestic wind tunnel test techniques in theory and improve the domestic wind tunnel test techniques, we analyzed the influence of broadband rolling road system on wind tunnel test after simulation. Simulation Details In order to reflect the condition differences between wide belt rolling road and without rolling road more factually, the digital model is quite similar to a real one, as shown in Fig. 1. 31


Turn static files into dynamic content formats.

Create a flipbook
Issuu converts static files into: digital portfolios, online yearbooks, online catalogs, digital photo albums and more. Sign up and create your flipbook.