Study On Pressure Wave And Aerodynamic Characteristics Of A Maglev Train Passing Through The Tunnel At 600km/h

The test speed of the maglev train can reach 600km/h,which greatly shortens the travel time of the passengers compared with the traditional wheel-rail trains.At the same time,the air flow can also exert a strong aerodynamic effect on the train.Especially when the maglev train passes through the tunnel at high speed,the air flow in the tunnel is more intense and complex due to the restrictions of the wall surface of the car body and the wall of the tunnel.The aerodynamic phenomenon is more intense than that on the clear line,which will have a great influence on the safety of the train and the comfort of the attendants.Therefore,it is necessary to study the aerodynamic performance of the maglev train at high speed through the tunnel and provide support for the development of high-speed maglev transportation technology in China.This paper takes the proposed high-speed maglev train model in our country as the research object,and uses the three-dimensional numerical simulation method to study the turbulent flow field characteristics and aerodynamic characteristics of the maglev train passing through the tunnel.Based on the pressure correction algorithm,RANS turbulence simulation method and SST k-? turbulence model are used to solve the three-dimensional,unsteady,compressible,turbulent flow of the external air when the maglev train passes through the tunnel at high speed,and the overlapping grid technology is used to realize the relative motion between the maglev train and the tunnel.First,in order to verify the correctness of the numerical simulation results of the maglev train passing through the tunnel process,a verification model for the train-tunnel numerical simulation calculation was established,and the correctness of the numerical calculation method and the grid partitioning strategy is verified by comparing with the test data of Japan's dynamic model.At the same time,it is verified that the overlapping grid technology is used to simulate the feasibility of the maglev train passing through the tunnel process.Secondly,the formation mechanism of the compression wave and the expansion wave in the course of the maglev train entering into the tunnel is analyzed.When the maglev train passes through the tunnel,because of the constant reflection superposition and propagation of the compression wave and the expansion wave in the tunnel,the distribution of the flow field changes with time,the compression wave causes the air pressure to rise,and the expansion wave causes the air pressure to decrease.When the maglev train passes through the tunnel at different operating speeds,the variation law of air pressure is roughly the same,and the higher the speed,the greater the pressure peak.Finally,the aerodynamic characteristics of the maglev train passing through the tunnel are analyzed.The aerodynamic resistance of train is closely related to the reflection superposition of tunnel pressure wave,and the drastic change of aerodynamic resistance is correlated with the abrupt change of pressure on the front and rear end of the train,when the train head enters the tunnel,the aerodynamic drag increases sharply,the aerodynamic resistance of the train body enters into the tunnel slowly increases linearly,and the aerodynamic resistance increases sharply again when the train tail enters the tunnel;When the maglev train enters or exits the tunnel,the aerodynamic lateral force will have obvious oscillation phenomenon,causing the vehicle body to swing to the right and left.when running in a tunnel,the aerodynamic lateral force direction is pointing close to the side of the tunnel wall;The aerodynamic lift direction of the maglev train is upward.As the train enters the tunnel,the aerodynamic lift will rise slightly and then decrease until the tail enters the tunnel it will rise again;As the train exits the tunnel,the aerodynamic lift will drop and then rise until the tail exits the tunnel it will drop again.When the maglev train passes through the tunnel at different operating speeds,the variation law of aerodynamic force is roughly the same,and the higher the speed,the greater the aerodynamic force peak.The aerodynamic force of the train running on the open line and the aerodynamic force in the tunnel is approximately squared with the speed.The aerodynamic force of the train in the open line and the mean of the aerodynamic force in the tunnel is approximately squared with the velocity.In this paper,the research results on the flow field characteristics and aerodynamic characteristics of the high-speed maglev train passing through the tunnel will provide a good basis for further systematic research in the future.