Tilt-rotor aircraft fuselage wall aeroacoustics radiation suppression using Higher harmonic control

Abstract

Aeroacoustics radiation is one of the main sources of tilt-rotor aircraft interior noise. In order to reduce the noise radiation on the surface of tilt-rotor aircraft fuselage, an active rotor control technology based on Higher Harmonic Control (HHC) is proposed. Its control effect is verified by simulation and the control mechanism is studied at the same time. Firstly, a tilt-rotor aeroacoustics prediction model is established based on FW-H equation and Beddoes unsteady aerodynamic model. And the accuracy of the above model is verified according to the flight test data of the XV-15 tilt-rotor aircraft. Furthermore, taking XV-15 as the object, a simulation research of rotor aeroacoustics active control is carried out in both airplane mode and helicopter mode. The simulation research reveals that: the HHC can suppress the aeroacoustics radiation of tilt-rotor to the fuselage through the principle of sound pressure cancellation. By applying appropriate control inputs, the maximum aeroacoustics radiation can be reduced by 9.2 dB in airplane mode; and the maximum aeroacoustics radiation can be reduced by 13.5 dB in helicopter mode.