强降雨环境下高速列车空气动力学性能

为研究强降雨对高速列车空气动力学性能的影响, 利用Euler-Lagrange方法建立了强降雨环境下高速列车空气动力学计算模型; 空气建模为连续相, 采用Euler方法描述, 雨滴建模为离散相, 采用Lagrange方法描述, 并采用相间耦合方法对降雨环境进行模拟; 分别开展列车气动性能计算及雨滴降落仿真, 并与试验数据进行对比, 验证计算方法的准确性; 数值仿真了强降雨环境下高速列车的流场结构和气动特性。计算结果表明: 随着降雨强度的增加, 在雨滴的冲击作用下, 流线型头型前端区域的正压逐渐增大, 流线型头型后端区域的负压逐渐减小, 从而导致头车气动阻力增大; 降雨强度对高速列车头车气动阻力系数的影响较为显著, 而对气动升力系数的影响较小; 与无降雨环境相比, 当降雨强度为100~500 mm·h^-1时, 200 km·h^-1车速下的气动阻力系数增加0.004 0~0.020 4, 气动阻力增加85~432 N, 增大率为2.64%~13.46%;300 km·h^-1车速下的气动阻力系数增加0.002 7~0.013 7, 气动阻力增加129~652 N, 增大率为1.78%~9.05%;400 km·h^-1车速下的气动阻力系数增加0.002 3~0.009 8, 气动阻力增加195~829 N, 增大率为1.52%~6.49%, 因此, 不同车速下, 气动阻力系数随着降雨强度的增加而增大, 且与降雨强度近似呈线性关系; 当车速为300 km·h^-1, 降雨强度为100 mm·h^-1, 雨滴粒径由2 mm增加为4 mm时, 气动阻力系数由0.152 0增大到0.154 9, 气动阻力增加138 N, 增大率为1.91%, 因此, 高速列车气动阻力系数随着雨滴粒径的增加而增大, 且与雨滴粒径近似呈线性关系。

Aerodynamic performance of high-speed train under heavy rain condition

In order to study the influence of heavy rain on the aerodynamic performance of a high-speed train, the aerodynamics computation model of high-speed train under heavy rain was established based on the Euler-Lagrange method. The air was modelled as the continuous phase, which was described by the Euler method. The raindrop was modelled as the discrete phase, which was described by the Lagrange method. The two-way coupled method was used to simulate the rainfall environment. The calculation of train aerodynamic performance and raindrop simulation were carried out, respectively, and the accuracy of the calculation method was verified by comparing with the experimental data. The flow field structure and aerodynamic performance of a high-speed train under heavy rain conditions were simulated numerically. Calculation result shows that with the increasing of rainfall intensity, under the impact of raindrops, the positive pressure on the front-end area of streamlined head increases, and the negative pressure on the back-end area of streamlined head decreases. As a result, the aerodynamic drag of head car increases. The rainfall intensity has great influence on the aerodynamic drag coefficient of the head car of a train, while has little influence on the aerodynamic lift coefficient. Compared with the aerodynamic drag coefficient under no rain conditions, when the rainfall intensity is 100-500 mm·h-1, for the train speed of 200 km·h-1, the aerodynamic drag coefficient increases by 0.004 0-0.020 4, the aerodynamic drag increases by 85-432 N, and the increasing percentage is 2.64%-13.46%. For the train speed of 300 km·h-1, the aerodynamic drag coefficient increases by 0.002 7-0.013 7, the aerodynamic drag increases by 129-652 N, and the increasing percentage is 1.78%-9.05%. For the train speed of 400 km·h-1, the aerodynamic drag coefficient increases by 0.002 3-0.009 8, the aerodynamic drag increases by 195-829 N, and the increasing percentage is 1.52%-6.49%. Therefore, the aerodynamic drag coefficient increases with the rainfall intensity at different train speeds, and there is an approximately linear relationship between the coefficient and the rainfall intensity. Under the train speed of 300 km·h-1 and the raindrop intensity of 100 mm·h-1, when the raindrop diameter increases from 2 mm to 4 mm, the aerodynamic drag coefficient increases from 0.152 0 to 0.154 9, the aerodynamic drag increases by 138 N, and the increasing percentage is 1.91 %. Therefore the aerodynamic drag coefficient of a high-speed train increases with the increasing of raindrop diameter, and there is an approximately linear relationship between the coefficient and the raindrop diameter.