Fu Min, Li Peng, Liang Xi-Feng
Key Laboratory of Rail Traffic Safety, Ministry of Education, School of Traffic & Transportation Engineering, Central South University, Changsha, Hunan, China.
PLoS One. 2017 Mar 31;12(3):e0175044. doi: 10.1371/journal.pone.0175044. eCollection 2017.
Analysis of the slipstream development around the high-speed trains in tunnels would provide references for assessing the transient gust loads on trackside workers and trackside furniture in tunnels. This paper focuses on the computational analysis of the slipstream caused by high-speed trains passing through double-track tunnels with a cross-sectional area of 100 m2. Three-dimensional unsteady compressible Reynolds-averaged Navier-Stokes equations and a realizable k-ε turbulence model were used to describe the airflow characteristics around a high-speed train in the tunnel. The moving boundary problem was treated using the sliding mesh technology. Three cases were simulated in this paper, including two tunnel lengths and two different configurations of the train. The train speed in these three cases was 250 km/h. The accuracy of the numerical method was validated by the experimental data from full-scale tests, and reasonable consistency was obtained. The results show that the flow field around the high-speed trains can be divided into three distinct regions: the region in front of the train nose, the annular region and the wake region. The slipstream development along the two sides of train is not in balance and offsets to the narrow side in the double-track tunnels. Due to the piston effect, the slipstream has a larger peak value in the tunnel than in open air. The tunnel length, train length and length ratio affect the slipstream velocities; in particular, the velocities increase with longer trains. Moreover, the propagation of pressure waves also induces the slipstream fluctuations: substantial velocity fluctuations mainly occur in front of the train, and weaken with the decrease in amplitude of the pressure wave.
分析高速列车在隧道中的滑流发展情况，可为评估隧道内轨道旁作业人员和轨道旁设施上的瞬态阵风荷载提供参考。本文重点对高速列车通过截面积为100平方米的双线隧道所引起的滑流进行计算分析。采用三维非定常可压缩雷诺平均纳维-斯托克斯方程和可实现的k-ε湍流模型来描述隧道内高速列车周围的气流特性。利用滑移网格技术处理移动边界问题。本文模拟了三种情况，包括两种隧道长度和两种不同的列车配置。这三种情况下列车速度均为250公里/小时。通过全尺寸试验的实验数据验证了数值方法的准确性，并获得了合理的一致性。结果表明，高速列车周围的流场可分为三个不同区域：列车头部前方区域、环形区域和尾流区域。列车两侧滑流发展不平衡，在双线隧道中向窄侧偏移。由于活塞效应，隧道内的滑流峰值比露天环境中的更大。隧道长度、列车长度和长度比会影响滑流速度；特别是，速度会随着列车长度的增加而增大。此外，压力波的传播也会引起滑流波动：较大的速度波动主要发生在列车前方，并随着压力波幅度的减小而减弱。
