Liquid film morphology and aerodynamic performance of a high-speed train under wind-rain environments

Abstract

The performance degradation of railway vehicles operating in wind-rain environments has attracted widespread attention in recent years. This work focuses on a numerical study of the liquid film morphology and train aerodynamic performance under wind-rain environments. The train aerodynamic model in wind-rain environments is set up using Eulerian–Lagrangian methodology, and validated with existing experimental results. The liquid film morphology of the train is discussed using the Lagrangian wall film (LWF) model. The aerodynamic characteristics such as liquid film morphology, surface pressure, shear stress, velocity contour, aerodynamic coefficient, etc., are then discussed in detail. The results show that, when the rainfall duration is constant, the liquid film becomes thicker as rainfall intensity is greater. As crosswind becomes stronger, the thickness of liquid film gathered on the train roof decreases, and the liquid film on the windward and leeward sides of the train becomes thicker. The shear stress on the train in wind-rain environments is obviously greater than that exposed to crosswind environments. For the reason of rainfall, the skin friction coefficient on the train also increases, which will have an impact on the frictional resistance. Rainfall would lead to an increase in the aerodynamic coefficient of trains operating in crosswind environments, especially for lift force coefficient and pitch moment coefficient.