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

TLDR: In this paper, the aerodynamic and aeroacoustic behavior of the flow past a simplified high-speed train bogie at scale 1:10 is studied using a two-stage hybrid method comprising computational fluid dynamics and acoustic analogy.

Abstract: Aerodynamic noise becomes significant for high-speed trains and its prediction in an industrial context is difficult to achieve. The aerodynamic and aeroacoustic behaviour of the flow past a simplified high-speed train bogie at scale 1:10 is studied using a two-stage hybrid method comprising computational fluid dynamics and acoustic analogy. The near-field unsteady flow is obtained by solving the Navier-Stokes equations numerically with the delayed detached-eddy model and the results are used to predict the far-field noise through the Ffowcs Williams-Hawkings method. The sound radiated from the same scaled bogie model is measured in an anechoic open-jet wind tunnel. The aeroacoustic characteristics of tandem wheelsets are also investigated for comparison. It is 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 are convected downstream 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 the 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 to the wheelsets of the bogie, the noise contribution from the bogie frame is relatively weaker.

Figures

Fig. 9. Sketch of receiver locations

Fig. 2. Structured mesh topology around the bogie

Fig. 5. Power spectral densities of pressure at bogie wake positions

Fig. 16. Noise directivity of whole geometry in vertical x-y plane

Fig. 15. Three-dimensional noise directivity for simplified bogie

Fig. 7. Power spectral densities of drag coefficients

Frequently asked questions

Q1. What have the authors contributed in "Flow behaviour and aeroacoustic characteristics of a simplified high-speed train bogie" ?

The aerodynamic and aeroacoustic behaviour of the flow past a simplified high-speed train bogie at scale 1:10 is studied using a two-stage hybrid method comprising computational fluid dynamics and acoustic analogy. 

Q2. What future works have the authors mentioned in the paper "Flow behaviour and aeroacoustic characteristics of a simplified high-speed train bogie" ?

Such factors need to be accounted for in future work.