| Automotive aerodynamics is a displine to analyze the velocity and the pressure of the flow around the car. Based on the fundamental laws, principles and methods of the fluid mechanics, automotive aerodynamics is used to study the aerodynamic forces and torque on the car and their effects on vehicle performance and modeling. Automobile aerodynamic characteristic is an important theoretical basis for automobile body modelling design and an important evaluation factors of the vehicle features. The wind tunnel test has always been an important method to study the automotive aerodynamics. A large number of the important conclusions are almost based on wind tunnel test results. But due to the structure complexity and expensive price of the wind tunnel special for automobile, there is only one automobile specialized wind tunnel in our country, Ground Transportation Wind Tunnel Center in Shanghai. This kind of the wind tunnel is not available for numerous institutions, which has been restricting the research of the automobile aerodynamics in our country. Therefore, the study on how to conduct automobile wind tunnel test in a non-special wind tunnel has important practical significance.In this thesis, Zhejiang University boundary layer wind tunnel is taken as the test platform, conducting further study on the test method of automotive wind tunnel experiment and data correction method with a typical automobile model, MIRA fast-back car model, and optimizing the ground simulation system based on the method of numerical simulation and experiment.Firstly, some automotive wind tunnel test theories are introduced, such as the characteristics and the performance requirements of an automobile wind tunnel, ground simulation system and the similarity criterion of wind tunnel experiments.Secondly, the experiment method is designed according to the equipments of Zhejiang University boundary layer wind tunnel. A 1/4 MIRA fast-back model is made and a support device with adjustable height is designed. Then the aerodynamic forces and pressures of the MIRA fast-back model are measured using the fixed board-model lifting method to remove the ground effect. The method of numerical simulation and experiment is proposed to remove the support interference. And the whole data correction method is designed.Finally, the scheme of the ground simulation is modified combining numerical simulation and experiment. And the feasibility and effectiveness of the optimization programme is validated through comparative analysis.The results of this thesis are significant to design automotive model wind tunnel test and study the data correction method. It can guide how to conduct automotive wind tunnel test in non-special wind tunnels. |
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