Development of the Aero-Acoustic Analysis Code for Predicting Rotorcraft Noise

Abstract

Tiltrotor aircraft are emerging as a next-generation rotorcraft configuration capable of combining vertical takeoff and landing (VTOL) capability with high-speed cruise performance. During flight mode transition, the rotors undergo tilt motion, which induces unsteady aerodynamic phenomena that significantly affect not only the flight performance but also the acoustic radiation characteristics of the aircraft. In particular, complex aerodynamic interactions such as rotor-rotor, rotor-fuselage, and rotor-wing interference occur during the mode transition, and accurate prediction of these effects requires the aeroacoustic analysis framework that incorporates detailed rotor geometry modeling and wake resolution. In this study, a mid-fidelity aeroacoustic simulation framework was developed by coupling a panel method-based aerodynamic solver, a vortex particle method for wake modeling, and the Farassat 1A formulation for noise prediction. The proposed framework was validated against experimental data for the HART II rotor and the XV-15 tiltrotor. The framework was applied to predict the noise levels of a full-configuration XV-15 tiltrotor model under various tilt angles. In particular, phase interference effects depending on the observer location were evaluated to examine the impact of destructive and constructive interference on the overall sound pressure level.