Aeroacoustic control mechanism on near-wall-wing of Aero-train based on plasma jet

Abstract

In this study, an aeroacoustic control mechanism of a plasma jet acting on a high-speed moving wing under a wing-in-ground effect is investigated. Moreover, a novel method is proposed to reduce the aeroacoustics of Aero-train wings. Numerical simulations of the aeroacoustics generated by flow around a National Advisory Committee for Aeronautics 4412 wing are performed under three different plasma excitation modes at four clearances with an incoming flow velocity of 0.3 Ma and an angle of attack of 5°. The results show that different plasma excitation modes interfere with the vortex generation and development in different ways to achieve aeroacoustic reduction. The UP excitation mode delays the airflow separation, delays the vortex generation and development, and reduces the vortex intensity. The BOTH excitation mode forces transverse vortices to transform into streamwise hairpin vortices and reduces the local pressure fluctuation intensity. Hence, plasma jets exhibit a good control effect on the peak aeroacoustics under different clearance conditions but result in the frequency shift effect of acoustic energy transfer to high frequencies. The modal analysis of the flow field of the three excitation conditions via a proper orthogonal decomposition method reveals that the trend of the modal change is similar for the three excitation conditions, and the change in each order of the modal corresponds to the energy decrease at the peak frequency and the energy increase at high frequencies.