Numerical investigation of the effect of cavity flow on high speed train pantograph aerodynamic noise

Abstract

Reducing train pantograph noise is particularly important. In this paper, the flow behaviour and noise contribution of simplified geometries representing high-speed train pantographs and the roof cavity at 1/10th scale are investigated. The Improved Delayed detached-Eddy Simulation (IDDES) turbulent model is used for the flow field simulation and the Ffowcs Williams & Hawkings aeroacoustic analogy is used for far-field noise prediction. The pantograph recess geometry is simplified to a rectangular cavity and two simplified DSA350 pantographs are included. The effect of the pantograph cavity is studied by comparing the flow behaviour and radiated noise from cases with and without the cavity, and also for different train running directions. When the pantographs are installed in a cavity, the shear layer, separated from the cavity leading edge, interacts with the pantographs, and generates large pressure fluctuations on the pantograph surfaces. In comparison with pantographs installed on a flat train roof, the flow around the pantographs with the cavity has different characteristics in terms of the velocity profile upstream of the pantographs. The study shows that the main noise source is from the panhead of the raised pantograph which produces strong tonal noise and this noise source is affected by the cavity flow.