Reduced scale simulation of the compression wave generated by the entry of a high-speed train into a tunnel

The development of high speed railway networks in Europe arises numerous problems concerning pressure waves generated in a tunnel when train enter it. This paper presents a reduced-scale test method, using low-sound-speed gas, which has been developed and evaluated. The test rig can reproduce train Mach numbers up to 0.34 even if its material speed is limited to about 50 m/s. Compared to the results obtained by full-scale tests, the results obtained with three dimensional models reproduce both the three dimensional characteristics of the compression wave at the entrance of the tunnel and the planar ones farther in the tunnel quite well. The study proved also that the planar compression waves in the tunnel can be well reproduced by means of a simpler axially symmetrical models, in so far as the longitudinal evolution of its cross sectional area is well represented.