针对汽车行驶中受侧风的影响问题,通过数值模拟研究了侧风作用下汽车的气动特性。利用三维软件UG 设定某实车模型参数,基于计算流体力学方法对实车模型进行数值模拟,研究侧风作用下车身外流场变化以及不同前车窗倾角对汽车气动特性的影响。结果表明,侧风中汽车外流场不对称,导致空气侧向力系数急剧增加达到0.927,空气阻力系数增加38.5%达到0.392,空气升力系数增加15.6%达到0.281;随着前车窗倾角的增大,车身底部气流在车尾的分离推迟,尾涡数量减少,车身表面正负压区域缩小,空气侧向力及空气升力系数变小,在前车窗倾角为35°时,汽车在侧风中的气动特性最优。
The aerodynamic characteristics of cars driving in crosswind are studied by numerical simulation. A real car model is established and the front window angle is modified by the three-dimensional software of UG. Then numerical simulations for these models are taken using the computational fluid mechanics method. The characteristics of the body outflow field in crosswind are analyzed as well as the influences of different front window angles on the aerodynamic characteristics. As a result, the body outflow field becomes no longer symmetrical and this leads to aerodynamic side force coefficient up to 0.927, aerodynamic drag coefficient increased by 38.5% (up to 0.392) and aerodynamic lift coefficient increased by 15.6% (up to 0.281). Meanwhile, the airflow separation from the bottom at the rear is postponed and the number of vortexes is reduced since the front window angle becomes larger. The areas of positive and negative pressures are smaller. When the front window angle is 35°, there is the best aerodynamic characteristic in crosswind.
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