Numerical simulations of the pressure waves and micro pressure waves generated by a high-speed train passing through an enclosed sound barrier

The pressure waves and micro pressure waves generated by high-speed trains passing through a circular enclosed sound barrier are numerically simulated with a moving-grid technique. Results show that: when a train passes a circular enclosed sound barrier, the pressure variations on the wall of the sound barrier are related to the generation, propagation, and reflection of compression and expansion waves. The pressure amplitude increases when the compression waves propagate towards measuring points on the wall, while the opposite is true for expansion waves. In the cross section of the sound barrier, pressure extrema at the measuring points near the train are larger than those at the measuring points far from the train, with a maximum difference about 28%. The difference of pressure amplitudes on the wall of the sound barrier and the maximum pressure on the nose tip of train heads are approximately proportional to the square of train speeds. When a train passes the sound barrier at a higher speed, micro-pressure waves will be generated at the exit of the sound barrier, whose extrema decreases rapidly as a function of the distance to the exit. The extreme values of micro-pressure waves are approximately proportional to the cube of train speeds.