Quantitative Effects of Velocity and Residual Pressure Level on Aerodynamic Noise of Ultra-High-Speed Maglev Trains

The challenge of aerodynamic noise is a key obstacle in the advancement of low-pressure tube ultra-high-speed maglev transportation, demanding urgent resolution. This study utilizes a broadband noise source model to perform a quantitative analysis of the aerodynamic noise produced by ultra-high-speed maglev trains operating in low-pressure environments. Initially, an external flow field calculation model for the ultra-high-speed maglev train is presented. Subsequently, numerical simulations based on the broadband noise source model are used to examine the noise characteristics. The impact of the train speed and pressure level on noise generation is investigated accordingly. Subsequently, a correlation formula is derived. The results reveal that the amplitude of sound source changes in the streamlined region of the head and tail cars of the train is large, and the amplitude of changes for the middle car is smaller. The noise source strength increases with speed, with a quadrupole noise source becoming dominant when the train speed exceeds 600 km/h. At a speed of 1000 km/h, the noise source intensity from the streamlined area at the rear of the train overcomes that at the front. Furthermore, the noise source decreases as the pressure level in the tube decreases. When the pressure level drops to 0.01 atm, the quadrupole noise source intensity of a train running at 600 km/h significantly weakens and falls below that of the dipole noise source.