轮拱罩充满率对整车气动特性的影响

针对某种小型轿车,基于计算流体力学(CFD)方法研究了不同轮拱罩充满率时旋转车轮对整车气动特性的影响,并与现有理想模型的试验结果对比.结果表明:在其他参数不变的情况下,随着轮拱罩充满率的下降,整车阻力系数上升,升力系数下降,当充满率下降27%时,阻力系数上升接近20%,升力系数下降接近30%.阻力上升主要是由于轮拱罩中的气流量增加,并且受轮拱罩结构的影响,内部流动分离加剧,导致尾流区的涡量均上升,车辆背压下降;升力下降主要是因为下车身气流速度加快,导致下车身压力减小.

Effect of Wheel Housing Filling Ratio on Aerodynamic Characteristics of Sedan

By using computational fluid dynamics(CFD), this paper studies the effect of rotating wheels with different filling ratios on the aerodynamic characteristics of wheel housings of a sedan. The results are compared with the existing experimental data. It is concluded that while the filling ratio drops by 27%, the total drag coefficient rises nearly by 20% and the lift coefficient drops almost by 30%. The main reason for the drag coefficient reduction is the increased flow rate inside the wheel housings, which generates more flow separations, higher vorticity and lower car base pressure. The lower lift coefficient results from the accelerated flow near the underbody, which leads to lower local pressure.