会车瞬态气动特性分析与研究

Analysis for Transient Aerodynamic Characteristics of Two Automobiles Passing Each Other

以某轿车实车为研究对象,应用滑移交界面和动网格技术对该轿车会车过程中的瞬态外流场进行了数值模拟,得到了会车过程中该轿车的阻力系数和侧力系数的瞬态变化趋势,结合流场剖面上的压力场和速度场,分析了这种变化趋势的原因,总结了会车过程中汽车瞬态气动特性.研究结果表明:在会车过程中两车周围的流场相互影响,车身受到的气动力在极短的时间内发生剧烈变化.当轿车与轿车会车时,轿车的气动阻力系数呈负正弦,侧力经历两个波峰和一个波谷.二者的变化不同步.当轿车与卡车会车时,轿车的阻力系数、侧力系数的变化趋势更复杂、更剧烈.

With sliding interface and moving mesh technique provided by STAR-CD software,the 3-D transient external flow field around two vehicles passing each other was simulated.The tendency of changing drag and side coefficient was provided.By analyzing the pressure distribution and velocity vector on some sections,the reasons for the tendency and transient aerodynamic characteristics were concluded.The data shows： in the case that two cars which have the same volume and shape pass each other,the tendency of changing drag coefficient is similar to negative sinusoid,and the side coefficient has three peak values;But in the case that a car and a container truck,whose volume and shape have huge differences,pass each other,the tendency is more complicated and intense.