Numerical Simulation Of Aerodynamic Effect On High Speed Train Out From Tunnel

High-speed train occupies an important position in the world transportation industry with its irreplaceable advantages. With the continuous improvement of the train running speed, the aerodynamic problem of the high speed train tunnel is becoming increasingly significant. When the high-speed train emerges from a tunnel, air flow space of exit gradually changed. The occurrence of the tunnel pressure wave, the outlet wave and the exit micro-pressure wave make the high-speed train aerodynamic performance changed, which effect trains safe operation and passengers comfort, especially under the wind environment. Therefore, the research on aerodynamic effect of high speed train out of the tunnel has very important significance.Take the CRH5 EMU and Hong-Xi Tunnel exit or nearby landscape of the second Lanchow-Sinkiang double-line as object for study the pressure field, velocity field and aerodynamic load in the process of the train out of the tunnel by means of numerical calculation method in this paper.Firstly, head compression wave and tail expansion wave formation mechanism and characteristic are studied with the train head or tail out of the tunnel. By analyzed the pressure field in tunnel and velocity changes near the exit, to explain the formation process of the front compression wave and rear expansion wave. The pressure change law of the front compression wave or the tail expansion wave is obtained by comparing and analyzing the pressure change in different position of the tunnel.Secondly, the formation mechanism and the fluctuation characteristics of the exit wave are studied. When the train pulled out of the tunnel, the pressure field and the velocity field near the tunnel-exit changed. The pressure change law of the exit wave is also obtained by comparative analysis of different location of the exit wave.Again, the characteristics of flow field on the train surface and around calculation area with the train in and out of the tunnel are studied. The changes of the flow field under different conditions were classical analyzed, which get the principle of the pressure change at different location. The extreme pressure value are compared in three different transit location, and obtained the preliminary effect of different transit section on train operation.Finally, the variation characteristics of train aerodynamic load are studied. Aerodynamic load of the train and four different cars are analyzed by comparison of peak on different conditions in the process of the train out of the tunnel to illustrate the influence of different condition on train.The above research results and rules can be as a basis for in-depth study of the high-speed train aerodynamics and provide a useful reference for the interpretation of the aerodynamic effect of high speed train pulled out of the tunnel.