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尾流结构对高速行驶车辆的经济性、操纵稳定性和安全性存在直接影响。建立典型阶背车仿真模型,在计算区域内进行网格划分,为提高分析精度对模型尾部进行网格加密。采用计算精度和稳定性较高k-ε标准双方程模型,对流项采用三阶迎风格式离散,压力速度耦合采用SIMPLE方法。对相同尺寸的实体缩尺模型进行风洞试验研究,结果表明:经过模型上表面气流在后视窗前缘发生分离,部分气流在后视窗与行李厢盖板之间的区域内形成回流,部分气流在行李厢盖上再附着并分离脱落;在压差作用下分离流与来自模型两侧的气流共同形成旋向相反的尾部涡流,随着距离的增加旋度逐渐减小,并在距模型尾部三倍车身长度附近涡流基本消失。
Wake structures have a direct impact on the economy, handling and safety of high-speed vehicles. A typical stepback vehicle simulation model is built, and the mesh is divided in the calculation area, and the tail of the model is encrypted by grid in order to improve the analysis accuracy. Adopting the k-ε standard two-equation model with high calculation accuracy and stability, the convection term is discretized by the third-order upwind scheme. The pressure-velocity coupling is SIMPLE method. Wind tunnel tests on solid scale models of the same size show that the partial air flow forms a backflow in the area between the rear window and the trunk lid, The lid of the trunk re-attached and separated off; under the pressure difference between the separation flow and the air flow from both sides of the model together to form the opposite direction of the tail vortex, as the distance increases curl gradually decreased, and from the tail of the model Three times the length of the body near the vortex disappeared.