Analysis of water film distribution and aerodynamic characteristics of high-speed train under rainfall environment

Abstract

In the rainfall environment, the water film is formed on the body surface of the high-speed train when raindrops impact the train. The water film interacts with the flow field around the train, thereby affects the aerodynamic characteristics of the high-speed train. In this paper, based on SST k-w turbulence model and Euler-Lagrange discrete phase model, the aerodynamic calculation model of high-speed train under rainfall environment is established, and LWF (Lagrangian wall film) is used to simulate the water film distribution and flow characteristics of train. Then the water film distribution and aerodynamic characteristics of high-speed train surface under different rainfall intensities were studied. The calculation results show that raindrops gather on the train surface to form water film under rainfall environment, and with the increase of rainfall time, the thickness and coverage range of water film expand, and the maximum thickness of water film can reach 4.95 mm. The average water film thickness of the train surface increases with rainfall intensity, which increases 3.26 times from 100mm/h to 500mm/h. The velocity of water film in the streamlined area of head car is larger, and the maximum velocity is 22.14m/s. The skin friction coefficient of high-speed train surface increases under rainfall condition. Compared with no rainfall condition, the average skin friction coefficient of train surface increases by 10.74% under rainfall intensity of 500mm/h. The head car positive pressure increases with the increase of rainfall intensity; with the increase of rainfall intensity, the drag coefficient of the head car increases.