Study of the Entry Compression Waves Induced by a High-Speed Train at the Entrance of Tunnel

초록

High-speed trains entering a tunnel portal creates a complicated system of pressure waves. The stationary air replaced by the high-speed train tries to escape through the gaps between the train and the tunnel, from the entrance, as a fluid jet. But, a part of it is pushed by the train nose profile. This air provokes the formation of a strong compression wave at the entrance, which then propagates further inside the tunnel, finally exiting as an impulsive noise. The current study focuses on the very first compression wave generated in the tunnel by a high-speed train. This wave is the most powerful factor, and its’ control shall indeed be the key to most aero-acoustic problems encountered. 3-D, unsteady, compressible Navier-Stokes equations were solved using implicit total variation diminishing schemes (TVD). The numerical scheme for this particular problem is validated against a reduced scale experimental study. The pressure being measured at five different points at different locations were used to study the changes in the compression waves. The entire flow physics is discussed using contours of pressure, velocity, temperature and Mach number.