Abstract: The aerodynamic study of automobile chassis is of practical significance for optimizing the aerodynamic performance of the whole vehicle and improving energy efficiency and range. Flattened chassis is constantly appearing in the design of new car models, and the study adopts computational fluid dynamics method to compare and analyze the aerodynamic performance of the whole car through numerical simulation technology. The results show that the flattened chassis design can reduce the wind resistance coefficient of the whole vehicle by about 3.45%, in which the flattened middle floor area of the whole vehicle changes the surface pressure from positive to negative, which enhances the stability of the whole vehicle in high-speed driving. The pressure in the exhaust pipe area in front of the sub-silencer is reduced by 71.5%, effectively reducing airflow separation. The rear floor flattening design can effectively guide the airflow away from the body, reduce the turbulence effect at the rear of the vehicle, and lower the air resistance. The study verifies the effectiveness of the chassis leveling design in improving the aerodynamic performance of the vehicle and provides data support for the aerodynamic optimization of the whole vehicle.

Key words: vehicle external flow field; flattened chassis; aerodynamic performance; aerodynamic drag coefficient

摘要： 汽车底盘的空气动力学研究对优化整车空气动力学性能、提升能效和续航里程具有实 践意义。平整化底盘在新车型设计中不断出现，该研究采用计算流体力学方法，通过数值仿 真技术对整车进行空气动力学性能对比分析。结果表明，经过平整化的底盘设计能降低整车 风阻系数约 3.45%，其中整车中地板区域平整化后，表面压力由正压力转为负压力，增强了 整车高速行车的稳定性；副消声器前端排气管区域压力降低 71.5%，有效减少气流分离；车 身后地板平整化设计可以有效引导气流远离车身，降低整车尾部的湍流效应，降低空气阻力。 研究验证了底盘平整化设计在提升车辆空气动力学性能方面的有效性，为整车的空气动力学 优化提供了数据支持。

关键词: 整车外流场；平整化底盘；空气动力学性能；空气阻力系数