A suction method to mitigate pressure waves induced by high-speed maglev trains passing through tunnels

Abstract

When a high-speed maglev train travels through a tunnel, sudden pressure changes are generated in the tunnel, which have a negative impact on the comfort of passengers and the service life of equipment. Moreover, a strong micro-pressure wave is radiated, causing environmental noise at the tunnel exit. Using the unsteady compressible Reynolds-averaged Navier–Stokes equations based on the shear stress transport k-ω turbulence model, this study investigates the effectiveness of suction (deployed on the tunnel wall) to mitigate the pressure waves and compares the results obtained under different suction velocities. The results show that when the suction is actuated, a low-pressure region is generated near the suction slots, which can trim down the initial compression wave and the high-pressure region in front of the train. Moreover, the instantaneous train surface pressure, tunnel surface pressure and micro-pressure wave have a significant relationship with the suction velocity. For instance, compared to the no suction case, the suction-actuated case with the suction velocity of 50 m/s contributes to an amplitude reduction of 10.44% and 30.61% for the first and second sudden pressure changes, respectively, at train surface measuring point H1 (at the nose of the train); an amplitude reduction of more than 14% for the sudden pressure change at tunnel surface measuring point T17 (at the middle of the tunnel); and an amplitude reduction of 12.44% for the micro-pressure wave at measuring point M2 (outside the tunnel and 20 m from the tunnel exit). These indicate that the suction technique can be employed to alleviate the tunnel aerodynamic effect. Also, the results obtained under different suction velocities can serve as a guide for the design of suction actuators.