In order to study the effects of flow field structures on the aerodynamic noise of pantograph,the numerical calculation of the flow field structure and aerodynamic field of high-speed pantograph is carried out by detached eddy simulation and FW-H equation.The differences of flow field characteristics,vortex structure and aerodynamic noise characteristics in two conditions of plane and concave boundaries are compared and analyzed,which provide reference for aeroacoustic optimization and simulation prediction of the local structure.The results indicate that the boundary forms can modify the local flow field obviously,and thus the velocity and vorticity fields are varied remarkably.Compared with the plane-boundary case,the scale of the vortices gets increased and the vortex structure becomes relatively orderly in the concave-boundary case.The sound pressure level of the pantograph surface is relatively low with the concave boundary condition,and the aerodynamic noise energy is mainly distributed in the low frequency band within 500 Hz.According to the features of Lamb vector divergence distribution,it is thought the type of aerodynamic source keeps unchanged for various boundary conditions,but the aerodynamic source is comparatively weak in the concave-boundary case.And the comparison of helicity distributions between the two cases implies that the flow field modified has an impact on turbulent energy transfer and efficiency of conversion into sound energy.
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