Research on Aerodynamic Noise Characteristics of Multipole Sound Sources of 400 km/h High Speed Train
The escalating speeds of high speed trains have led to the emergence of obvious multi-source features of aerodynamic noise generated by trains,characterized by pronounced high speed motion effects and an elevated presence of quadrupole sound sources.The consequential impact is considerable on the far-field noise generated by trains.Leveraging the hybrid CAA methodology,based on the vortex sound theory and Lighthill acoustic analogy method,this study analyzed the flow field,aerodynamic noise,and far-field acoustic propagation properties adjacent to the pantograph structure at a speed of 400 km/h.The influence exerted by quadrupole sound sources on acoustic radiation was studied.The results reveal that the complex vortex movement near the wall surface,induced by the rapid movement of pantograph structure constitutes the primary aerodynamic noise source.These vortex structures predominantly cluster around the head,underframe,and insulator.The high turbulence areas stemming from the high speed movement of the pantograph mainly occur in the vicinity of the main poles,contributing to an amplification of the body's quadrupole sound source.Intense turbulence arises from surface flow separation on the components in this area.The maximum intensity of the quadrupole sound source reaches approximately 0.4 times that of the dipole sound source,with a lower sound field energy conversion efficiency compared to the dipole source.The total near-field sound pressure level of the pantograph peaks at 136 dB,and the main frequencies of acoustic radiation in the far-field,across different directions,converge within the same frequency band.The spectral profile as a whole reflects multi-peak characteristics.The quadrupole source energy contributes to 38.3％of the overall aerodynamic noise stemming from the pantograph of a high speed train running at 400 km/h.
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