复杂底部结构下的重型载货汽车气动阻力

Aerodynamic drag of heavy duty vehicle with complex underbody structure

针对具有复杂底部结构的五轴重型载货汽车气动阻力进行研究,建立了与实车外形结构一致的车辆模型,利用基于格子玻尔兹曼方法的计算流体动力学软件XFlow,模拟了模型外流场流体的宏观行为。进行了模型的格子尺度优化试验,得到整车模型的空气阻力系数以及底部结构对整车气动阻力的影响。对模型底部压力分布、旋转车轮的表面速度分布、模型底部外流场速度分布、湍流强度分布以及车辆模型底部粒子轨迹线进行了分析,根据分析结果对车辆模型底部进行结构优化。仿真结果表明:车辆模型的空气阻力系数误差在6%以内,对模型底部结构进行优化可以降低整车空气阻力系数23%。

The aerodynamic drag of five axes heavy duty vehicle with complex underbody structure was studied. The model with the real vehicle structure shape was established. Then, the macroscopic behavior of fluids in external flow field was simulated using the computational fluid dynamics software XFlow , which is based on Lattice Boltzmann Method. The air resistance coefficient of the whole vehicle model was obtained by lattice scale optimization test, and the influence of the underbody structure on the aerodynamic drag was investigated. The vehicle surface pressure distribution, the surface velocity field of the rotating wheels, the velocity distribution in the external flow field of the model, the turbulence intensity distribution, and the particle trajectories under the vehicle were analyzed. Results show that the drag coefficient error of the truck model is within 6 % . Through the underbody structure optimization, the aerodynamic drag coefficient of the whole vehicle model can be reduced by 23 %.