抄録
A simulation method for full helicopter configuration is constructed by combining an unsteady Euler code and an aeroacoustic code based on the Ffowcs-Williams and Hawkings formulation. The flow field and helicopter noise are calculated using a moving overlapped grid system, and the mutual effect of main rotor and tail rotor are studied for the helicopter in hover or forward flight. In the hovering flight calculation, the tip vortex of the tail rotor is dragged by the induced flow of the main rotor, and the detailed phenomena of the flow pattern are captured well. In a forward-flight calculation, noises from the main rotor and tail rotor are predicted to understand the tail rotor noise for both self noise and the interaction noise with the main-rotor wake. Comparison of noise magnitude shows that the relative importance of tail rotor noise with respect to the main rotor noise according to the flight conditions.
