Dynamic Behaviour Analysis of Emu Train Entering and Exiting Tunnels Using Aerodynamic Load Data

Abstract

To study the change of aerodynamic load pressure when the EMU (Electric Multiple Unit) enters and exits the tunnel, the corresponding aerodynamic equation is established. By analysing the development process of EMU trains under mechatronics, a research background for the air pressure problem caused by the speed increase of high-speed trains is displayed. Furthermore, the aerodynamic problems and related pressure waves in the tunnel of the training group are introduced. Based on the aerodynamic load data, the lateral vibration characteristics of the train are analysed. It is proposed that after the train enters the tunnel, the surrounding air generates pressure waves and expansion waves due to the restriction of the train surface and the tunnel wall. Subsequently, the Bernoulli equation is used to calculate the pressure values of the train under different running conditions in the tunnel. Finally, the ANSYS Fluent fluid calculation software is used to simulate the aerodynamics of the train tunnel of the EMU. The results show that, affected by space constraints and air compressibility, when the train enters the tunnel, the compression wave changes from three-dimensional to one-dimensional. After the head of the train enters the tunnel, the average pressure value at the cross-section of x=2D increases rapidly. At t=0.011 second, the average pressure of the cross-section increases slowly, and the rate of change reaches the maximum. At t=0.027 second, the average pressure of the cross-section reaches the maximum. When the train approaches the cross-section, the pressure value at the sampling point close to the train body changes much greater than the change rate of the other two sampling points. The simulation results show that the transverse force of the train in the tunnel is 0.45Kn. Therefore, when the train travels in the tunnel, it will be subject to more complicated aerodynamic load conditions. This study will provide references for studying the aerodynamics of high-speed trains passing through tunnels.