流线型长度对重联高速列车明线运行气动性能的影响

Influence of streamlined length on aerodynamic performance of double unit high-speed train running in open air

为了研究重联列车的空气动力学特征,首先,建立了3种不同头部流线型长度的列车模型,其中重联列车计算模型由2列3辆编组的列车连挂组成,非重联列车计算模型为6辆编组;其次,使用三维、定常、不可压缩N-S方程和RANS方法对列车明线匀速运行时的流场进行模拟计算,并验证网格无关性和算法准确性;最后,对比分析了重联区域的特殊结构对列车气动性能的影响。研究结果表明:在运行条件相同时,重联列车的阻力始终大于非重联列车的阻力,但随着列车运行速度增加,两者的阻力差异逐渐降低,当列车运行速度为350 km/h时,两者阻力相对误差为14.5%;增加车头流线型长度能显著降低列车气动阻力和升力,且对重联列车减阻效果更显著。流线型长度从6 m增加到12 m,重联列车与非重联列车气动阻力分别降低了15.9%和12.5%;重联列车头车和尾车的升力分别降低27.8%和43.7%,与非重联列车头、尾车升力降低幅度基本一致;流线型长度变化对重联列车各节车辆的气动力影响并不一致;随着流线型长度增加,重联区域前部相邻车辆的阻力增加,后方相邻车辆的阻力则逐渐减小。受自身结构对称性影响,重联区域前后两列列车表面压力变化梯度具有较高的一致性,仅数值上存在差异。

To analyze the aerodynamic performances of double unit high-speed train,firstly,three kinds of train models with different streamlined lengths were established,in which the model of double unit high-speed train is composed of two trains with 3-car formation,and the model of normal high-speed train is 6-car formation.Secondly,the three-dimensional,steady,incompressible N−S equation and RNS method were used to simulate the flow field of the train running at a constant speed in open air.The grid independence and algorithm accuracy were verified.Finally,the influence of the special structure of the couple region on the aerodynamic performance of the train was compared and analyzed.The results show that under identical running conditions,the drag of a double unit high-speed train surpasses that of the normal train.Nevertheless,as the train speed increases,the disparity in aerodynamic drag between the two gradually diminishes.At the speed of 350 km/h,the relative difference in aerodynamic drag between the two types is 14.5%.Moreover,increasing the streamlined length of the head car leads to a substantial reduction in the aerodynamic drag and lift,with a more pronounced drag reduction effect observed in the double unit train.Extending the streamlined length from 6 m to 12 m will reduce the aerodynamic drag of the double unit train and normal train by 15.9%and 12.5%,respectively.The lift of the head and tail cars of the double unit train decreases by 27.8%and 43.7%,respectively,which is basically consistent with that of the normal train.Furthermore,alterations in streamlined length yield heterogeneous aerodynamic effects on individual vehicles within a double unit train.With the increase of the streamlined length,the drag of neighboring vehicles at the leading end of the couple region demonstrates an increment,whereas the drag of adjacent vehicles at the trailing end gradually diminishes.Affected by the inherent symmetry of its own structure,the surface pressure gradient of both trains before and after the couple region exhibits notable consistency,with only marginal variations in numerical values.