轿车并列行驶湍流特性的数值模拟

Numerical Simulation on Characteristics of Turbulent Flow around Two Cars Driving Side-by-side

为了研究复数车辆并列行驶的湍流特性对交通安全的影响,采用移动地面模拟轿车相对地面的运动和旋转壁面模拟车轮转动的方法,进行了两辆轿车并列行驶外部流场湍流特性的数值模拟研究。以单倍车宽侧向间距的两辆轿车为典型算例,给出了汽车车身表面的速度和压力分布,并讨论了右侧轿车尾部流场3个典型截面的速度分布和尾部流线分布情况。重点对比了0.1、0.3、0.5、1、2倍车宽间距的两车流场的流线分布情况。右侧轿车侧向力系数的对比分析说明:随着两车侧向间距的减小,迅速增大的侧向力将两车压向彼此。为保证行驶安全性和操纵稳定性,两车并列行驶的安全距离应该在单倍车宽与0.5倍车宽之间。

To study the effect of the turbulent flow around 2 cars driving side-by-side on the traffic safety, the turbulent flow field was numerically simulated where the ground effect was imitated by the moving wall boundary condition and the rotating wheel effect was imitated by the rotating wall boundary condition. Taking 2 car models driving side-by-side with a side space of a car as an example, the velocity and pressure distributions on the car models surface were given. The velocity distributions in 3 typical sections and streamline distribution in the right car model wake were presented and discussed. The streamline distributions in the flow field around 2 cars with the side space of 0.1,0.3,0.5,1 and 2 times of car width were compared. The simulated aerodynamic force coefficients were compared with the wind tunnel test value of the single car model with stationary and rotating wheels. The analysis of the sideforce on the right car model showed that with the reducing side spaces, the rapidly increasing side forces push 2 cars to each other, and the safe side space should be 0.5~1.0 times of the car width for the driving and steering safety.