柔性飘带长度对Ahmed模型气动阻力的影响

为降低汽车行驶过程中的气动阻力，以尾部倾角为25°的Ahmed类车体模型为研究对象，提出在其尾部垂直面下边缘添加不同长度柔性飘带的控制方法，采用格子玻尔兹曼方法与有限元分析相结合的流固耦合计算方法，探讨了柔性飘带长度对汽车气动阻力的影响。首先对汽车模型进行格子尺度优化，得到模型的空气阻力系数；然后研究了柔性飘带对汽车气动阻力的影响；最后对模型尾部流场、柔性飘带附近流场以及模型尾部表面压力系数进行了分析。仿真结果表明：在模型尾部添加适当长度的柔性飘带，改善了尾流结构，提升了尾部表面压力，减小了车体的压差阻力，减阻率最高为12.25%。

Effect of flexible ribbon length on aerodynamic drag of Ahmed model

In order to reduce the aerodynamic drag of the vehicle during driving, the Ahmed body model with a tail angle of 25° was taken as the research object. The control method of adding different lengths of flexible ribbons to the lower edge of the vertical plane of the tail was proposed. The fluid-solid coupling calculation method combining lattice Boltzmann method and finite element analysis was used to explore the influence of the length of the flexible ribbon on the aerodynamic drag of the vehicle. Firstly, the air resistance coefficient of the model was obtained by optimizing the lattice scale of the vehicle model. Then, the influence of the flexible ribbon on the aerodynamic drag of the vehicle was studied. Finally, the tail flow field of the model, the flow field near the flexible ribbon and the pressure coefficient of the tail surface of the model was analyzed. The simulation results show that adding a flexible ribbon of appropriate length to the tail of the model improves the wake structure, increases the pressure on the tail surface, and reduces the differential pressure resistance of the vehicle body. The maximum drag reduction rate is 12.25 %.