Numerical study on the quadrupole sound source in aerodynamic noise of high-speed pantographs

Insufficient consideration of aerodynamic noise source will affect the accurate evaluation of high-speed pantograph noise. In this study, we present an approach to separate and quantify the dipole and quadrupole noises of pantographs. The improved delayed detached eddy simulation (IDDES) was used for turbulence modelling and two acoustic surface integral methods were used to predict the noise. The results show that the pantograph noise is caused by the vortex shedding and interaction in the wake. The running speed does not change the distribution of the two aerodynamic noise sources, but the intensity increases significantly. Although the quadrupole noise increases with the speed level, the dipole noise still dominates. The sound pressure levels of the two noise sources increased by about 60 log10V and 70 similar to 80 log10V, respectively. The noise energy is concentrated in 160-2500 Hz, and the dominant frequency is proportional to the speed level.