Abstract: Air pressure pulse in tunnel when two high-speed trains passing by each other is greater than that in open air when trains running at the same speed, the reason is that complicated pressure pulses produced by trains running into the tunnel is added to the pressure pulse of two trains passing by each other. Several important questions during the trains passing-by have not been clearly studied yet, including change of pressure pulse on the trains; relationship between tunnel entrance pressure pulse and trains passing by pressure pulse; how large the pressure pulse is and how the pressure pulse changes with trains’ running speed. By means of 3D numerical analysis of computational fluid dynamics, the dynamic process of trains passing by each other in tunnel is simulated. The combine relationship of the pressure pulses produced at tunnel entrance and produced by trains passing by is proved. The developing trend of pressure pulse on moving train is obtained. The calculation formula of the maximum minus pressure peak on train as a function of train speed is derived. The study results can potentially be used as a reference basis for aerodynamically designing of high-speed trains and high-speed railways tunnels.

Key words: High-speed train, Pressure pulse, Trains passing by each other, Tunnels