Analysis of the near-field and far-field sound pressure generated by high-speed trains pantograph system

Abstract

Due to the limited understanding of spatial sound field and contribution of pantograph, a deep analysis is presented to extract understanding the aerodynamic noise characteristics of high-speed trains pantograph system. The near-field and far-field noise are predicted by the acoustic perturbation equations and Ffowcs Williams-Hawkings equation, respectively. The spatial sound propagation is analyzed by proper orthogonal decomposition and cluster-based reduced-order modelling. The flow field results predicted by large eddy simulation show that the flow behind pantograph is governed by hierarchical structures, which occurs to be featured with three layers as well as periodic evolution. The dipole source is dominated in far-field radiated noise while the quadrupole source is negligible, since the intensity of the quadrupole source is less than that of the dipole source. The contribution rates of base-frame, pan-head, groove, upper-arm, horn, lower-arm and rod-insulator are higher than the other components, and the radiated sound energy of them accounts for approximately 90% of the total energy. The noise contribution of pan-head exceeds 10% at the frequency of 1000 Hz. Base-frame is the largest contributor, and more than 6% of noise contribution occurs at the frequency of 630 Hz. The spatial sound propagation includes two major aspects: one is mainly reflected upwind from groove, and the other is propagated with the center of groove. The results highlight the possibility to develop a new design of high-speed trains pantographs, in order to obtain an aerodynamic noise reduction.