高速列车隧道会车流场的CFD分离涡数值模拟

目的研究高速列车隧道会车压力波及列车尾流特性。方法建立某型高速列车三节车模型,采用脱体涡方法数值模拟两列车以350km/h在隧道内等速会车的流场。数值模拟的空间离散化压力项、密度项及修正的湍流黏度项使用二阶迎风格式,动量项使用有界中心差分格式,时间离散采用预处理二阶精度差分格式,用壁面函数处理隧道壁,使用雷诺时均法作方法对比。计算列车车头、侧墙及尾车等部位的压力时间历程,然后使用傅里叶变换对尾车测点进行频谱分析,最后对尾流中不同位置的湍流强度进行分析。结果头车所受压力波动最为剧烈,中间车次之,尾车最小。列车侧墙同一垂向位置不同高度压力变化相差不大。列车尾涡主频在3.85Hz附近,其可能对列车横向振动有一定的影响。结论尾涡是两个不断向后发展的中等强度涡旋,在充分发展段,其湍流强度会有一个较为明显的抬升,之后逐渐减弱。会车侧涡流由于横向发展较为迅速,导致其强度较小且减弱速度较快。

CFD Detached-eddy Numerical Simulation of High Speed Train Intersecting in Tunnel

Objective To study the pressure fluctuation and wake flow characteristics of high-speed train tunnels intersecting in tunnel. Methods A three-car model of a high-speed train was established and the flow field of two trains intersecting in a tunnel at 350 km/h was simulated by the detached eddy method. The spatial discretization pressure term, density term and the modified turbulent viscosity term were simulated by the second-order upwind; the momentum term was simulated by the bounded central difference, the time discretization was simulated by the second-order precision difference; and the tunnel wall was treated with a wall function and Reynolds time-averaged method was also used for comparison. The pressure time history of the front, side wall and tail of the train was calculated. Then the spectrum of the measured points of the tail car was analyzed by Fourier transform. Finally, the turbulence intensity at different positions in the tail flow was analyzed. Results The pressure fluctuation of the front car was the most violent, that of the middle car was the second, and that of the rear car was the smallest. The pressure variation of the side wall of the train at the same vertical position and at different heights was not significant. The main frequency of wake vortex was around 3.85 Hz, which may have some influence on the lateral vibration of train. Conclusion The wake vortices are two moderately strong vortices which develop backward continuously. In the fully developed stage, the turbulence intensity will increase obviously and then decrease gradually. Because of the rapid development of the lateral eddy current, the strength of eddy in meeting-side is small and its weakening speed is fast.