Aerodynamic of the trains in tunnels

[摘要] When a train moves through air, it generates a turbulent flow around it called a slipstream. The slipstream is associated with high air velocities and rapidly-changing pressure fields. These aerodynamic issues are still valid when a train passes a tunnel and in addition to these, the compressibility of the air around high-speed trains produces what are called “micro-pressure waves” as a result of running in a confined space. The air velocity, pressure variation and direction of the flow inside tunnels is different to the slipstream in open air. These differences depend on the size of the tunnel (cross section and length of the tunnel) and the shape and speed of the train. In the present thesis, the effect of tunnel length on the flow and pressure inside is investigated. The investigation uses computational fluid dynamics techniques (CFD), in which a 1/25th model of the ICE2 train is used. Two tunnel lengths are investigated; one is double the length of the other. The sliding technique is employed to simulate the movement of the train in the tunnel. The simulation uses unsteady RANS and applies the Shear Stress Transport (SST) turbulence model. The effect of tunnel length on both pressure and velocity fields is discussed. The variation of the pressure at the entrance and exit of the tunnel is also analysed and conclusions are drawn.

[发布机构] University:University of Birmingham;Department:School of Engineering, Department of Civil Engineering

[关键词] T Technology;TF Railroad engineering and operation