道路不平致车身俯仰运动对气动升力影响研究

The Influence of Pitching Motion Induced by Road Roughness on Aerodynamic Lift

为了探究路面不平产生的车身俯仰运动对气动升力的影响,结合汽车动力学参数与路面参数,得到不同路面空间频率下的车身俯仰运动规律,并利用重叠网格技术实现了车身绕质心的正弦俯仰运动,通过对比风洞试验数据验证了湍流模型的准确性。通过车身表面压力、车身周围流场结构分析了车身俯仰时的气动升力变化规律。结果表明,同一俯仰角下,车尾下摆时产生的气动升力数值大于车尾上摆;车尾下摆时,由于前轮腔的“吸力”效应,车底气流速度降低;车尾上摆时,由于前轮腔的“排斥”效应,车底气流速度增大。

To explore the influence of the body pitching motion caused by uneven road surfaces on aerodynamic lift,the paper combined the vehicle dynamics parameters and road surface parameters to obtain the body pitching motion laws under different road surface spatial frequencies.By using the overlapping grid method,the sinusoidal pitching motion of the body around the center of mass was achieved.The accuracy of the turbulence model was verified through comparison with the wind tunnel test data.By analyzing the surface pressure on the vehicle body and the flow field structure around it,the paper discussed the variation law of aerodynamic lift during the pitching motion.The results show that for the same pitch angle,the aerodynamic lift value generated when the tail swings downward is greater than that when the tail swings upward.During the downward tail swing,the airflow velocity at the bottom of the vehicle decreases due to the"suction"effect in the front wheel well.Conversely,the“repulsion”effect in the wheel well increases the airflow velocity during the upward tail swing.