Aerodynamic noise reduction of high-speed pantograph by introducing planar jet on leeward surface of panhead.

Combining the improved delayed detached eddy simulation (IDDES) model and Ffowcs Williams-Hawkings (FW–H) equation, the potential of panhead leeward-side jet in pantograph aerodynamic noise control is numerically investigated. A typical double-strip pantograph is used as the baseline model. Two identical planar jets are arranged on the leeward side of the two strips to achieve active flow control. The results show that the planar jet can reduce the aerodynamic drag of the upstream strip and suppress its lift fluctuation, while the jet does not produce equivalent level of positive effects on the downstream strip. Benefiting from the suppression of lift fluctuation of the upstream strip, the far-field noise of the model equipped with jet achieves a 7 dB reduction in the main direction of panhead lift fluctuation, and the noise on the pantograph side is also reduced by 1–2 dB. The flow-field analysis reveals that the planar jet pushes the coherent flow structures in the panhead's wake downstream, which makes the high-intensity flow-field fluctuation away from the upstream strip. The absence of the positive effect of the jet on wake flow modification of the downstream strip can be attributed to the distinct inflow conditions of the two strips. • The panhead leeward jet can suppress the lift fluctuation of the upstream strip but has few effect on the downstream one. • The panhead leeward jet can reduce the pantograph aerodynamic noise. • The panhead leeward jet elongates the shear layer of the upstream strip and pushes the coherent structures downstream. • The different effects of the jet on the two strips' wake are due to their different inflow conditions. [ABSTRACT FROM AUTHOR]