Characteristics of Lateral Aerodynamic Force Variation of 160 km/h Train Passing through Tunnels

Abstract

Objective At a speed of 160 km/h, a certain EMU in China exhibits good stability when running on open tracks. However, when passing through single-track tunnels, the tail car experiences periodic lateral swaying issues. Thus, it is necessary to conduct an in-depth study on the aerodynamic characteristics of the train when passing through tunnels. Method Using numerical simulation methods, a three-dimensional compressible transient simulation model of a certain EMU with bogies is established based on the RNG k-epsilon turbulent model and sliding mesh technology. The study focused on the variation surface pressure on the tail car when the train passes through tunnels. Simultaneously, the transient nature of the lateral aerodynamic force characteristics of the train is analyzed in both time and frequency domains. Result & Conclusion The research results indicate that due to the restriction of airflow by the tunnel walls and the effect of the train's wake flow, there exists a pressure difference on both sides of the train body with aliternating characteristics when passing through tunnel. Furthermore, the alternation of lateral forces on the tail car is more pronounced. The lateral forces acting on the train exhibit low-frequency periodic alternation, with a main frequency of approximately 2.2 Hz. The aerodynamic effect is the strongest when the tail car just enters the tunnel, resulting in the largest fluctuation in lateral force amplitude. The variation in train lateral force can be used as a boundary condition for analyzing the vehicle lateral stability.

Keywords

• bullet train
• tail car lateral sway
• tunnel
• aerodynamic load
• main frequency of lateral force
• vortex shedding