An evaluation of a rotating Kirchhoff acoustic methodology

Rotorcraft Impulsive (i.e. High-Speed Impulsive (HSI) and Blade-Vortex Interaction (BVI)) noise for advancing rotors is studied numerically. The unsteady transonic Full-Potential Rotor (FPR or FPRBVI) code is used for the simulation of the nearfield flow. A rotating Kirchhoff's method has been installed in the TRAC (TiltRotor Aeroacoustic Codes) system of NASA Langley and is used for the extension to the acoustic far-field. The results are compared to available experiments and results from the acoustic analogy code WOPWOP. Results for both HSI and BVI (including both independently-generated and self-generated vortices) are presented and compared with several experiments. The results show that the rotating Kirchhoff noise method is becoming a very valuable tool for rotorcraft impulsive noise prediction and can complement codes based on the acoustic analogy method.