不同侧风工况下汽车稳定性双向耦合研究

Two-way Coupling Analysis of Vehicle Stability in Different Crosswind Conditions

为了研究汽车在自然侧风环境下的稳定性,建立了汽车空气动力学与汽车多体系统动力学的实时双向耦合仿真系统,并通过风洞试验验证了空气动力学模拟方法的准确性,通过调整风压中心的方法分析了汽车多体系统动力学模型的鲁棒性。采用动边界方法对ISO12021汽车侧风稳定性试验工况进行了单向和双向耦合分析研究,并将汽车在标准工况下的侧风稳定性模拟结果与自然侧风模拟结果进行对比分析。研究结果表明:汽车在标准侧风工况下的车身姿态变化会反过来影响汽车周围流场的变化,特别是底部流场和背风侧流场,汽车在侧风下的运动同时受侧风和悬架的共同作用,对汽车侧风稳定性的研究需要采用双向耦合分析方法;相较于标准侧风,自然侧风对汽车周围流场的作用更加迅速和不稳定,峰值气动侧力和横摆力矩使汽车稳定性较标准侧风更差。对汽车侧风稳定性的评价需要综合考虑不同侧风工况的影响。

In order to study the vehicle stability in natural crosswind,a real-time two-way coupling approach was established,which coupled the vehicle aerodynamics with vehicle multi-body dynamics.And the aerodynamics simulation method was verified by wind tunnel tests.The robustness of vehicle multi-body dynamics model was analyzed with the translation of pressure center.According to the requirements of ISO12021,the moving boundary method was used to investigate the necessity to conduct the two-way coupling by comparing the results of the both methods.Then the vehicle stability in different crosswinds was discussed with the comparison of natural crosswind conditions and ISO12021 conditions.The results show that the change of the vehicle posture in crosswind conditions will also affect the flow fields around the vehicle in turn,especially the flow field on the vehicle bottom and windward side.The vehicle motion is affected by the combined effects of crosswind and suspension.It is essential to conduct the two-way coupling to study vehicle crosswind stability.The impacts of natural crosswinds on the flow fields around the vehicle are faster and more unstable than that of the standard conditions.And the unstable flow field leads to peak aerodynamic forces,which make the vehicle stability worse in natural crosswinds than that in standard crosswind conditions.The evaluation of vehicle crosswind stability needs to consider the influences of different crosswind conditions.