Abstract
We aim to study the characteristics and mechanism of the aerodynamic noise sources for a high-speed train in a tunnel at the speeds of 50 m/s, 70 m/s, 83 m/s, and 97 m/s by means of the numerical wind tunnel model and the nonreflective boundary condition. First, the large eddy simulation model was used to simulate the fluctuating flow field around a 1/8 scale model of a high-speed train that consists of three connected vehicles with bogies in the tunnel. Next, the spectral characteristics of the aerodynamic noise source for the high-speed train were obtained by performing a Fourier transform on the fluctuating pressure. Finally, the mechanism of the aerodynamic noise was studied using the sound theory of cavity flow and the flow field structure. The results show that the spectrum pattern of the sound source energy presented broadband and multipeak characteristics for the high-speed train. The dominant distribution frequency range is from 100 Hz to 4 kHz for the high-speed train, accounting for approximately 95.1% of the total sound source energy. The peak frequencies are 400 Hz and 800 Hz. The sound source energy at 400 Hz and 800 Hz is primarily from the bogie cavities. The spectrum pattern of the sound source energy has frequency similarity for the bottom structure of the streamlined part of the head vehicle. The induced mode of the sound source energy is probably the dynamic oscillation mode of the cavity and the resonant oscillation mode of the cavity for the under-car structure at 400 Hz and 800 Hz, respectively. The numerical computation model was checked by the wind tunnel test results.
Highlights
High-speed trains have become the preferred vehicle for middle- and long-distance travel
We aim to study the characteristics and mechanism of the aerodynamic noise sources for a high-speed train in a tunnel at the speeds of 50 m/s, 70 m/s, 83 m/s, and 97 m/s by means of the numerical wind tunnel model and the nonreflective boundary condition
The results show that the spectrum pattern of the sound source energy presented broadband and multipeak characteristics for the highspeed train
Summary
High-speed trains have become the preferred vehicle for middle- and long-distance travel. The spectrum of the sound source located downstream of the wheel arches had multipeak frequencies near 600 Hz. In 2012, Lauterbach et al [12] studied the Reynolds number effect of aerodynamic noise on a 1/25 scale model of a high-speed train in the aeroacoustic wind tunnel of the German Aerospace Center in Brunswick and in the cryogenic wind tunnel of the DNW (German-Dutch wind tunnels) in Cologne. This paper attempts to introduce a nonreflective boundary condition based on the numerical model of aerodynamic noise calculation for high-speed trains on an open track to study the flow field structure, the aerodynamic noise source intensity distribution characteristics/spectral characteristics, and their mutual relations in an infinite tunnel.
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