Flow behaviour and aeroacoustic characteristics of a simplified high-speed train bogie

Abstract

Aerodynamic noise can be a significant problem in the operation of high-speed trains; its prediction is difficult to achieve in an industrial context. The aerodynamic and aeroacoustic behaviour of the flow past a simplified high-speed train bogie at scale 1:10 is studied in this paper; the utilized approach is a two-stage hybrid method that consists in computational fluid dynamics and computational acoustics studies. The near-field unsteady flow was obtained by numerically solving the Navier–Stokes equations with the delayed detached-eddy model and the results were used to predict the far-field noise using the Ffowcs-Williams – Hawkings method. The sound radiated from the same scaled bogie model was measured in an anechoic open-jet wind tunnel. The aeroacoustic characteristics of tandem wheelsets were also investigated for comparison purposes. It was found that the unsteady flow past the bogie is characterized by coherently alternating vortex shedding from the axles and more randomly distributed vortices of various scales and orientations from the wheels and frame. The vortices formed behind the upstream geometries move downstream due to convection and impinge on the downstream bodies, generating a highly turbulent wake behind the bogie. The noise predictions correspond fairly well with the experimental measurements for the dominant frequency of tonal noise and the shape of spectra. Vortex shedding from the axles generates tonal noise, with the dominant peak corresponding to the vortex-shedding frequency. The directivity exhibits a dipole shape for the noise radiated from the bogie. Compared with the wheelsets of the bogie, the noise contribution from the bogie frame is relatively weak.