车窗对车辆侧向气动性能影响的数值模拟

Influence of window on train side aerodynamic performance by numerical simulation

采用基于Spalart-Allmaras方程的分离涡模拟(DES)数值模拟方法,就车窗外形对车辆侧向气动性能及流场结构的影响进行分析计算。研究结果表明:车窗对车辆侧向气动性能有较大的影响:和粘帖车窗车体相比,采用凹陷车窗的车辆侧向力系数由0.71变为1.20,升力系数由1.28变为1.74,倾覆力矩系数由-0.27变为-0.63;受凹陷车窗影响,车体顶部气流速度下降,背风区脱落涡被吸附到车窗附近,此处涡核线较多且杂乱;远处涡核较长,脱落涡直径较大;而粘帖车窗车体顶部气流流速较高,背风区脱落涡尺寸较大,且位于靠近车体的部位。数量较多,尺寸较小。

Using DES based on Spalart-Allmaras equation,the influence of the side windows on lateral aerodynamic performance and the flow field structure was analyzed and calculated.The results show that the side window has great impact on aerodynamic performance.Compared to the aerodynamic coefficients of body with pasted windows,the lateral force coefficient,side force coefficient and overturning moment coefficient of vehicle with sunken windows vary from 0.71,1.28,-0.27 to 1.20,1.74,-0.63,respectively.Windows affect the flow field in leeward section.Restrained by the sunken windows,flow velocity over the roof drops and flow separation in the back of the vehicle is weak,which makes the shedding vortexes attracted by the windows where the vortex core lines are more and messy,while the vortex core lines far away are longer and vortexes have large diameter.To the body with pasted windows,the velocity of airflow pasting the roof is higher and flow separation in the leeward area is serious where there are large vortexes and the internal flow velocity is low,and there are many vortexes close to the car-body which are messy and in small size too.