Numerical study on aerodynamic noises and characteristics of the high-speed train in the open air and tunnel environment

When high-speed trains were passing through a tunnel, pressure wave will change seriously and cause large aerodynamic loads, which may bring problems to the comfort of passengers and the aerodynamic fatigue failure of train bodies, components and fixed equipment in the tunnel. Therefore, this paper systematically studied aerodynamic characteristics of a high-speed train under three kinds of situation including open air, entering a tunnel and completely in a tunnel, experimentally verified the correctness of numerically computational model. In the open air, vortexes of the high-speed train were mainly distributed in the bogie and compartment connections. Sound pressure level curves had many peak and valley points and the maximum sound pressure level was 72 dB. Sound pressure levels gradually decreased with the increase of analyzed frequency. In addition, sound energy was mainly distributed below 2000 Hz. Aerodynamic noises presented an obvious directivity and attenuation distribution. In the entering the tunnel, peak and valley values of pressures at train head and tail appeared at different time. The maximum pressures at the observation points of train head and tail were 345 Pa and –450 Pa respectively, while the minimum negative pressures at the observation points of train head and tail were –2900 Pa and –3260 Pa respectively. Computational pressures of observation points were basically consistent with the experimental test, and the relative error was only within 2 %, which indicated that the adopted numerical simulation can better simulate aerodynamic characteristics of the high-speed train. The change of the length of the tunnel had no an obvious effect on the aerodynamic lift of the high-speed train. When the length of the tunnel was less than 800 m, the negative peak of the aerodynamic lift increased continuously with the extension of the tunnel, but the increased rate was gradually reduced. When the length of the tunnel was more than 800 m, the negative peak of the aerodynamic lift was gradually reduced. According to the acoustic panel contribution, these panels which had an obvious effect on the interior noise of the high-speed train were recognized. Composite sound absorption material was then applied to these panels and the interior noise at the observation points was improved obviously.