Abstract
This study employs a numerical approach that combines compressible detached eddy simulation (DES) with the Ffowcs Williams-Hawkings (FW-H) equation to investigate the potential of employing a slot jet at the leading edge of the bogie cavity for reducing bogie aerodynamic noise. The simulation is conducted on a 1:8 scale shortened train model, and two jet fluxes are considered. The permeable surface formula of the FW-H equation is adopted for far-field noise calculation to account for the scattering and shielding effects of the vehicle body and track structures, as well as the quadrupole source contribution. The results reveal that the slot jet induces a notable lifting effect on the shear layer formed at the leading edge of the bogie cavity, consequently reducing the impact of the shear vortex structures on the lower part of the bogie and the rear wall of the bogie cavity. However, as the shear vortex structures are guided towards the track, their interactions with the track structures are intensified. Due to the slow attenuation of the turbulent wake of the bogie region, it is difficult to avoid the spurious sound sources (hydrodynamic pressure fluctuations) induced by the wake passing through the integral surface by merely adjusting the position of downstream integral surface, while the end cap averaging technology can effectively filter out these spurious sources. The introduction of the jet primarily reduces the far-field noise below 1600 Hz of the bogie region, with higher jet velocity resulting in improved noise reduction effects.
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