有无车轮对低风阻车型气动特性的影响

Influence of Presence or Absence of Wheels on Aerodynamic Characteristics of Low-Resistance Vehicles

针对有无车轮低风阻电动汽车模型进行数值计算,并通过对两种模型是气动力、表面压力、速度场等计算结果对比,评估了有无车轮对低风阻车型气动特性的影响。研究表明:车轮的存在使得整车气动阻力增大63.8%,其中各部件的贡献从大到小依次为前轮室、车身前部、背部、车底(负贡献)、后轮室;而升力增大一倍多,主要来源于车底的贡献;流场结果显示车轮对车身的气动作用体现在车轮带来的全局阻塞和局部尾迹两种效应的综合影响;后轮及后轮导流罩产生的尾迹会导致低阻车尾部涡环强度增强,回流区长度减小,背压降低。综合气动阻力、升力、压力分布和流场对比分析,明确了车轮的存在会给低风阻车型带来较大的气动特性变化。

Numerical calculations are conducted for the low-resistance electric vehicle model with or without wheels,and the aerodynamic force,surface pressure,velocity field,and other calculation results of the two models are compared to evaluate the influence of wheels on the aerodynamic characteristics of the low-resistance vehicle.The results show that the presence of wheels increases the aerodynamic drag of the vehicle by 63.8%.The components which have the largest contribution are the front wheel chamber,the front of the vehicle body,the base,the underbody(negative contribution)and the rear wheel housing in descending order.The vehicle lift increases more than doubled,mainly due to the contribution of the underbody of the vehicle.The aerodynamic influence of the wheels on the vehicle is reflected in the combined effect of global blocking and local wake caused by the wheel.The wake generated by the rear wheel and the rear guide hood will enhance the strength of the tail vortex ring and reduce the length of the backflow area and the base pressure.A comparison of aerodynamic drag,lift force,pressure distribution,and flow field shows that the existence of wheels will bring significant changes to the aerodynamic characteristics of the vehicles of low wind resistance.