Numerical Study On The Pressure Fluctuation Induced By High-speed Train Entering The Tunnel Based On The Coupling Method

Initial compression waves are generated before the head of high-speed train when itentering the tunnel. When the Initial compression waves propagate to the tunnel outlet, part ofthem radiate to the tunnel exit, formed micro-pressure waves when its strength is largeenough, it could cause serious influence on tunnel surrounding environment and residents.Tunnel pressure waves are formed in the process of train passing through the tunnel, it willinfluence the comfort of drivers and passengers when pass into carriages. Therefore, it hasrealistic meaning and practical value to simulate the initial compression waves and the tunnelpressure waves accurately.In this paper, the tunnel pressure waves that are generated when the high-speed trainentering tunnel are studied based on the method of vortex sound theory. In the process of thehead of train entering tunnel, the train head equivalent point source and replace by monopolesource to simulate the initial compression waves. In addition, comparing the initialcompression waves when the head of train replaced by monopole sources and replace bymonopole sources and dipole sources. In the process of train body entering, the influence ofthe exit flow vortex and separated flow are considered. In the process of the rear of trainentering, it equivalent point sink and replace by monopole sources and dipole sources. Thenumerical simulation results of initial compression wave and tunnel pressure wave are agreedwith the experimental data of abroad. Based on the method of vortex sound theory, studyingthe influence of the head shape of revolution cone, paraboloid, ellipsoid, blunt body train anddifferent speed on the initial compression waves and the pressure change rate. The fittingequation of compression wave of maximum pressure and maximum pressure gradient withvelocity has given at the four different head shape.This article coupled the method of vortex sound theory and characteristics based on theone-dimensional compressible unsteady non-homentropic flow model for the first time,improved the method of characteristics which can’t simulate train head type before. In theprocess of high-speed train entering the tunnel, using the method of vortex sound theory tocalculate the pressure wave in the strong three-dimensional effect region near the front andthe rear of train, other regions using the method of characteristics. The correctness of thiscoupled method is verified by comparing with the experimental data. Based on the couplingmethod, studied the influence of the head shape and train speed on tunnel pressure wave andthe rate of pressure change.In this paper, the coupling method have achieved more accurate simulation about thepressure wave which induced by the train entered the tunnel with smaller computer resource. Some researching methods and conclusions of this paper can provide a beneficial referencefor relevant designers.