Research on jet control and noise reduction mechanism of sound source for leading bogie region

Abstract

In order to achieve sound source reduction in the leading bogie region, turbulent flow and near-filed acoustic pressure were solved based on large eddy simulation and acoustic perturbation equations. The noise control effectiveness of the jet control was confirmed through 1:5 scale high-speed trains model wind tunnel test and the numerical simulation method was validated. The effect of jet control at different positions, velocities and directions were evaluated. Notably, the Bogie-Jet-0.35 V scheme, which involves applying a jet flow at 0.35 times the incoming flow velocity at the leading edge of the bogie, exhibited superior control performance. Compared to the base condition, the optimal scheme achieved optimized control of acoustic and turbulent pressures, resulting in reductions of 2.0 dB and 2.7 dB, respectively. An improved reduced order method based on sample entropy was developed to explore the jet control mechanism. It was found that in the snapshots with high acoustic energy, the acoustic energy was primarily concentrated at the front and rear edges of the bogie. Jet flow reduced the turbulent pressure fluctuation energy near the front wheelset of the bogie. Additionally, jet flow reduced the probability of unsteady flow state transitioning to clusters with high acoustic pressure.