Abstract
To study unsteady aerodynamic noise characteristics in the connection position of high-speed trains, this paper established a computational model for aerodynamic noises in the connection position of high-speed trains based on computational fluid dynamics theories. This model included 2 middle trains and 1 connection structure. The detached eddy simulation (DES) was adopted to conduct a numerical simulation for the flow field around high-speed trains which were running in the open air without crosswind. The acoustic model of Ffowcs Williams-Hawkings (FW-H) was used to conduct an unsteady computation for far field aerodynamic noises in the connection position of high-speed trains. In the meanwhile, the boundary element method (BEM) was also applied to conduct an unsteady computation for the radiation of near field aerodynamic noises in the connection position. When the running speed was 250 km/h, time-domain characteristics, frequency-domain characteristics and sound propagation characteristics of aerodynamic noises in the connection position and the unsteady flow field around the connection position were obtained. Studied results showed that: vortex shedding and fluid separations in the connection position were main reasons for aerodynamic noises. In addition, main aerodynamic noise sources were at the recess and rear (the second train) in the connection position, and the first train was not an aerodynamic noise source. Peak frequencies of aerodynamic noises in the far field were 34 Hz, 79 Hz, 124 Hz and 170 Hz. When observation points were 7.5 m away from the center line of track, the maximum sound pressure level was 83.6 dB. When observation points were 25 m away from the center line of track, the maximum sound pressure level was 75.9 dB.
Highlights
Speed is the eternal pursuit of transportation
When the train ran at the speed of 300 km/h, aerodynamic noises caused by trains would be more than wheel-rail noises and became the main noise of high-speed trains [8]
Vortex shedding in the connection position further intensified noise radiation in the windshield
Summary
Speed is the eternal pursuit of transportation. In recent decades, high-speed trains have achieved rapid development in the world due to comfort, efficiency, safety and reliability. Studies on the aerodynamic noise of high-speed trains are mainly conducted through numerical computation. Through conducting wind tunnel test on high-speed trains, Wu [18] pointed out that the connection position was an obvious aerodynamic noise source and numerically studied the impact of structural form of windshield on aerodynamic noises. The paper only studied the impact of the connection position on near field aerodynamic noises of high-speed trains and did not involve far field radiation noises. Choi [21] conducted a wind tunnel test to study the aerodynamic noise of the connection position. This paper combined DES with BEM to conduct a numerical computation for the near field and far field aerodynamic radiation noise in the connection position of a three-dimensional high-speed train. To save computational time and ensure computational accuracy, the model maintained train body structures in the front and rear of the connection position
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