Study on the flow behaviour and aerodynamic noise characteristics of a high-speed pantograph under crosswinds

摘要

The aerodynamic noise of high-speed trains increases significantly under crosswinds.Researches have typically focused on the characteristics of aerodynamic loads and the corresponding safety issues,with less attention to flow-induced noise characteristics.In the present paper,the near-field unsteady flow behaviour around a pantograph was analysed using a large eddy simulation.The far-field aerodynamic noise from a pantograph was predicted using the Ffowcs Williams-Hawkings acoustic analogy.The results showed that asymmetric characteristics of the flow field could be observed using the turbulent kinetic energy and the instantaneous vortexes in crosswind conditions.Vortex shedding,flow separation and recombination around the pantograph were the key factors for aerodynamic noise generation.The directivity of the noise radiation was inclined towards the leeward side of the pantograph.The aerodynamic noise propagation pattern can be considered as a typical point source on spherical waves when the transverse distance from the pantograph geometrical centre is farther than 8 m.The sound pressure level grew approximately as the 6 th power of the pantograph speed.The peak frequency exhibited a linear relationship with the crosswind velocity.The numerical simulation results and wind tunnel experiments had high consistency in the full frequency domain,namely,the peak frequency distribution range,the main frequency amplitude and the spectral distribution shape.