Numerical investigation on flow and flow-induced noise behaviour of simplified high-speed train leading car with bogie fairing

The aerodynamic and aeroacoustic behaviour of flow past a simplified high-speed train leading car with bogie fairing is studied based on the theory of vortex sound and the acoustic analogy method. The near-field unsteady flow is obtained by the delayed detached-eddy model and the results are used to predict the far-field noise. It is found that the unsteady flow past the leading car is characterized by the vortices of various scales and orientations separated from the geometries. The vortices formed behind the upstream geometries are convected downstream and impinge on the downstream bodies，generating a highly turbulent wake behind the leading car. The volume dipole is larger than the volume quadrupole and becomes the predominate source of the quadrupole noise generated around the leading car. Strong flow separations and vortex sheddings are developed in regions of the noise，bogies，bogie cavities，and rear parts of the leading car where the large wall pressure fluctuations are generated and the dipole noise of high level is produced correspondingly. After the bogie cavities are covered by the fairings，the noise radiated from the rear bogie is higher than the leading bogie in the horizontal plane along the bogie center. The intensity of the aerodynamic noise radiated to the trackside direction is distributed even with the noise level of the front region a little higher than the rear part. The current leading car model can effectively mitigate the turbulence fluctuation and flow interaction in the key regions with the bogie cavities shielded by the bogie fairings and consequently reduce the aerodynamic noise generation and radiation.