Aerodynamic performance and flow evolution of a high-speed train exiting a tunnel with crosswinds

Sudden changes in the aerodynamic loads acting on trains can result in derailment or overturning. The impacts of infrastructure scenarios on the aerodynamic performance of trains are significant. When high-speed trains travel from one infrastructure scenario to another one, the aerodynamic loads and flow field will change suddenly. It is a commonly in western China for HSTs to exit a tunnel with crosswinds. In order to investigate the aerodynamic loads and the flow evolution, a three-dimensional, compressible, unsteady Reynolds Averaged Navier-Stokes method was utilized to simulate the process of a train exiting a tunnel under crosswinds. Results show that the flow field and the pressure varied significantly in the horizonal plane while the train exited the tunnel under crosswinds. In addition, the aerodynamic loads of each carriage which varied abruptly resulted in complex dynamic responses of the train including lateral variation, snake-like locomotion, and pitching motion. Furthermore, the variation magnitudes of Delta C-side, Delta C-lift, and Delta C-RM for the head carriage were 4.1, 2.2 and 1.6 times for the middle carriage, and 7.9, 8.1 and 8.2 times for the rear carriage. Therefore, the aerodynamic performance of the head carriage was the worst and the risk of accidents was the highest under crosswinds.