车身简化对不同轮辐下整车气动阻力变化趋势的影响

针对某A级轿车,首先通过整车风洞试验验证了计算流体力学仿真方法的可靠性,接着基于该数值计算方法,对复杂车身数模进行了封闭格栅、轮拱罩并平顺底部的简化处理,研究了车身简化对不同轮辐工况下整车气动阻力系数变化趋势的影响。结果显示,简化前后阻力系数趋势发生了改变,前后轮和车底部流场出现了明显变化。在此基础上,仅针对发动机复杂的舱内部件进行了不同程度的简化,结果显示,阻力系数趋势对舱内部件的简化也很敏感。因此,在以降低整车气动阻力为目标进行车轮局部优化时,需要谨慎地进行车身的简化工作。

Influences of Body Simplification on Aerodynamic Drag of a Sedan Under Different Rim Design Conditions

By means of computational fluid dynamics, this paper studies the effects of body simplification on the aerodynamic drag of a sedan under different rim design conditions. First, the numerical method is verified in a wind tunnel experiment. Then, the grille and wheel housings of the detailed sedan model are sealed while its bottom is flattened. The results show that the drag varies and the flow field around the wheels as well as at the bottom also obviously differs after simplification. Finally, the detailed parts inside the engine bay are simplified while the grille and the detailed bottom are kept. The results show that the drag is also very sensitive to the simplification inside the engine bay. Therefore, great care should be taken in body simplification when optimizing the wheels for lowering the aerodynamic drag of the vehicle.