Study On The Influences Between Automotive Underbody Shape And Aerodynamic Performance

Aerodynamic performance of automobiles, the key to decide the success of automobiles in the furious market competition, is the critical factor influenced the maneuverability, the safety, the economy and the comfort. Automobile style with the best aerodynamic shape will have a permanent vitality.During the past two decades, most of efforts to improve aerodynamic performance were focusing on the front, upper and rear shape optimizations. On the contrary, there were very limited studies on the underbody because of its geometrical complexity and difficult experiments to simulate effectively the flow field between the underbody and the ground. And little is known in this area. However, the aerodynamic drag from the unsmoothed underbody is the main part of the total aerodynamic drag. Besides, aerodynamic lift depends strongly on the underbody. Therefore, it is reasonable to regard the underbody as a prospective region for better aerodynamic performance, especially for high speed cars. And it is significant to carry out underbody aerodynamic characteristics of the underbody,The object of this research is to reduce the aerodynamic drag and improve the maneuverability for a 20% scaled sedan model through the underbody flow optimization using CFD. The aerodynamic coefficient varying mechanism caused by different underbody shape designs was analyzed. Computational results will provide recommendations for underbody design and make foundation of continuing to study the underbody flow mechanism and the underbody flow optimization.The digital models of this research consists of two groups, one group is generated for the study of the influences of the rough underbody shapes on the aerodynamic characteristics, the other is for the influences of the rear...