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Flow structure and far-field noise of high-speed train under ballast track
Abstract The flow structure and far-field noise of 1:8 three-carriage high-speed train under ballast track were investigated. The random surface of ballast track was established using the stochastic function method, and the flow field and far-field noise were calculated through large eddy simulation and FW-H equation at 250 km/h. Based on the wind tunnel test, the far-field noise errors of simulation are lower than 3 dB at most frequencies, indicating that the simulation method has an acceptable prediction accuracy. The bogies' sections were analyzed through reduced-order decomposition method, and the side vortex is found as the typical unsteady flow structure, while the near-ground flow is chaotic. Under the moving smooth ground, the first three bogies are affected by the jet shear layer generated under the cowcatcher. The flow structure is more chaotic, and the dipole sound sources’ energy is also stronger than that under the ballast track. The total sound pressure level of far-field noise under ballast track is 78.4 dB(A), which is 1.1 dB lower than that under the moving smooth ground. Considering the sound absorption effect of ballast track, based on the sound absorption coefficients of 17 cm ballast layer, the far-field noise is further reduced by 3.9 dB.
Highlights A reasonable ballast-track modeling method considering the statistical characteristics of ballasts is proposed. The reduced-order method is used to understand the unsteady flow structures of high-speed train under ballast track. The far-field noise and dipole source distributions under ballasted track and smooth ground are analyzed. The effect of rough structure and sound absorption in reduction of far-field noise under the ballast track are discussed.
Flow structure and far-field noise of high-speed train under ballast track
Abstract The flow structure and far-field noise of 1:8 three-carriage high-speed train under ballast track were investigated. The random surface of ballast track was established using the stochastic function method, and the flow field and far-field noise were calculated through large eddy simulation and FW-H equation at 250 km/h. Based on the wind tunnel test, the far-field noise errors of simulation are lower than 3 dB at most frequencies, indicating that the simulation method has an acceptable prediction accuracy. The bogies' sections were analyzed through reduced-order decomposition method, and the side vortex is found as the typical unsteady flow structure, while the near-ground flow is chaotic. Under the moving smooth ground, the first three bogies are affected by the jet shear layer generated under the cowcatcher. The flow structure is more chaotic, and the dipole sound sources’ energy is also stronger than that under the ballast track. The total sound pressure level of far-field noise under ballast track is 78.4 dB(A), which is 1.1 dB lower than that under the moving smooth ground. Considering the sound absorption effect of ballast track, based on the sound absorption coefficients of 17 cm ballast layer, the far-field noise is further reduced by 3.9 dB.
Highlights A reasonable ballast-track modeling method considering the statistical characteristics of ballasts is proposed. The reduced-order method is used to understand the unsteady flow structures of high-speed train under ballast track. The far-field noise and dipole source distributions under ballasted track and smooth ground are analyzed. The effect of rough structure and sound absorption in reduction of far-field noise under the ballast track are discussed.
Flow structure and far-field noise of high-speed train under ballast track
Zhuo-ming, Li (author) / Qi-liang, Li (author) / Zhi-gang, Yang (author)
2021-11-20
Article (Journal)
Electronic Resource
English
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