非光滑表面对汽车尾涡结构的控制分析研究

Research on Non-smooth Surfaces for Control of the Automobile Trailing Vortex Structure

车身气动阻力直接影响汽车的动力性和燃油经济性,尾涡结构对于车辆空气阻力的形成有很大的影响,非光滑结构在车身的合理布置能有效地减小汽车的空气阻力。为了研究车身非光滑结构对汽车尾涡结构的影响与控制,将凹坑型非光滑单元分别布置在MIRA阶梯背模型尾部、顶部、行李舱盖等表面,运用计算流体力学(Computational fluid dynamics,CFD)数值仿真与风洞试验相结合的方法,对比分析车身表面光滑模型与车身表面非光滑模型尾部流场的压力、湍流耗散率、速度矢量等参数的影响,探讨非光滑结构的扰动效应及其对尾涡形成的控制作用,得出非光滑结构能延迟气流分离,控制后风窗上猫眼涡与尾部剪切涡流,也能抑制汽车尾部主涡的生成。为有效控制车辆尾迹中旋涡结构,抑制涡激振动,改善汽车气动特性提供重要依据。

The aerodynamic drag of the body directly affects the power performance and fuel economy of the vehicle. Trailing vortex structure for vehicle has great effect on the formation of air resistance. The reasonable arrangement of the non-smooth structure in the body can effectively reduce the air resistance of the car. In order to study the influence and control to automobile tail vortex of the structure of non-smooth body, this article has pit type non-smooth units respectively arranging in the MIRA ladder back model of the top of the automobile and the trunk deck surface and the top of the automobile tail. By using the method of computational fluid dynamics（CFD） numerical simulation and wind tunnel test combination to comparative analysis of non-smooth surface of the tail of the model of pressure, turbulent dissipation rate, velocity vector and the effects of other parameters. The effect of non-smooth structure perturbation and the control of the formation of wake vortex are investigated.Concluded that the non-smooth structure can delay the flow separation,control the wind window on the cat and the tail vortex shear vortex and restrain the generation of the main vortex in the rear end of the vehicle. For the effective controlling of the wake vortex structure of the automobile, inhibition of vortex-induced vibration, improving the aerodynamic characteristics of the car to provide important basis.