STUDY ON MECHANISM OF COMPRESSION WAVE INDUCED BY A HIGH-SPEED TRAIN ENTERING A TUNNEL WITH HOLES ON HOOD

A cell-centered finite volume scheme for numerical integrations of Navier-Stokes equations for a three-dimensional unsteady viscous compressible isentropic flow has been presented here to simulate the compression wave produced by a train passing through a tunnel with an entrance hood. 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 sliding mesh technique. The paper studies on the effect of aperture opening ratio on the compression wave and compression gradient. The result indicates a hood with aperture openings can effectively decrease the maximum pressure and pressure gradient. No matter how long the hood is, the larger aperture opening ratio is, the more the compression grade will be. The longer the hood is, the more increasing ratio of the compression grade is. The maximum of compression grade is increasing with the length of hood. Once the length of hood is fixed, the length of aperture openings for entrance of tunnel has limit effects on the maximum pressure gradient.