Effective Tunnel Entrance Shape for Reducing Micro-pressure Wave Generated by the Entry of High-speed Train into a Tunnel

摘要

When a train nose enters a tunnel at high speed, an impulsive pressure wave called micro-pressure wave or tunnel sonic boom radiates from the tunnel exit and causes an explosive sound or an abrupt rattling of window frames or shutters of houses near the tunnel exit. Therefore it is necessary to seek for proper measures to solve this environmental problem for the speed-up of the existing railway and the construction of new high-speed railway in China. In this paper, the effect of the tunnel entrance shape on compression wave is investigated using numerical simulation. At first, a three-dimensional CFD model was built based on the compressible Navier-Stokes equations and k-ε turbulent model, and finite volume method was used to simulate the compression pressure wave generated by the entry of a high-speed train into a tunnel. The CFD model employed the techniques of moving mesh and arbitrary connectivity to simulate the relative motion between the mesh blocks that define flow domains of the high-speed train and the blocks of the tunnel. Then the numerical calculated pressure distribution inside the tunnel illustrating the compression wave is compared with that of field measurement and a qualitative agreement is found between them. At last, the compression waves and micro-pressure waves generated by the entry of a high-speed train into a tunnel with vertical and gradient entrance are calculated respectively. By analyzing the numerical results, a relative optimal tunnel entrance shape is proposed.