Mitigation of micro-pressure wave at high-speed maglev tunnel exit by resonant cavity structure

During the passage of the high-speed maglev train through the tunnel, the air flow in front is compressed due to the limitation of annular space formed by the inner wall of the tunnel and the surface of the car body, forming an initial compression wave. The initial compression wave propagates to the tunnel portal at the local sound speed, and some of it radiates outward to form a micro-pressure wave, which seriously affects the tunnel portal environment. This problem is even more pronounced when high-speed maglev trains reach speeds of 600 km/h. Therefore, a tunnel with a resonant cavity structure is proposed, and the three-dimensional, unsteady, compressible N–S equation and SST k–ω turbulence model are used to study the aerodynamic effect mitigation characteristics of the maglev train passing through the tunnel at high speed. The simulation comparison and dynamic model test verification of different resonator schemes are carried out. The results show that the resonant cavity structure installed in the redundant space in the tunnel can dissipate the compressed wave energy, reduce the rate of pressure change of the compression wave, and have a significant slowing effect on the micro-pressure wave at the tunnel opening. Compared with the existing tunnel, the resonator structure has a micro-pressure wave mitigation effect of 41.87% and 40.05% at 20 m and 50 m to the tunnel portal, respectively. The micro-pressure wave mitigation effect is linearly related to the number of resonators in the tunnel. The results of the moving model test show that the slowdown effect of the micro-pressure wave is positively correlated with the operating speed.