NUMERICAL SIMULATION ON MECHANISM OF COMPRESSION WAVE GENERATED BY A HIGH-SPEED TRAIN ENTERING A TUNNEL WITH A HOOD FOR PASSENGER SPECIAL LINE

A cell-centered finite volume scheme for numerical integrations of Navier-Stokes equations for a three-dimensional unsteady viscous compressible isentropic flow to simulate the compression wave generated by a high-speed train entering a tunnel with an entrance hood has been presented. The numerical procedure is based on pre-conditioned second-order accurate backward difference in time, and the relative motion between the train and tunnel is treated with a dynamic mesh technique. The paper focusing on the effect of a hood on transient pressure and pressure gradient of the compression wave aims to design an entrance hood for the passenger special line from Beijing to Shanghai. An entrance hood can reduce transient pressure value in the tunnel to some extent. In contrast, pressure gradient of the compression wave could be significantly decreased. On one hand, a hood extends the increasing time for pressure of the compression wave. On the other hand, the compression wave and expansion wave formed by the wave reflected among the entrance of the hood, train and tunnel could be superimposed, which could reduce the amplitude of pressure. The result also shows that a hood with a C type enlargement section is an optimum choice for the passenger special line from Beijing to Shanghai under consideration of reducing pressure gradient.