BVI Noise Predictions by Moving Overlapped Grid Method

The predictions of helicopter Blade-Vortex Interaction (BVI) noise are performed using a combined method of an unsteady Euler code with an aeroacoustic code based on the Ffowcs Williams and Hawkings formulation. A moving overlapped grid method is employed in the Euler code. Three types of grids, blade grid, inner and outer background grids are used. The calculated waveform of BVI noise clearly showed the distinct spikes caused by the interaction between blade and tip vortex. The carpet noise contours calculated by the present method was compared with the experimental data obtained by Advanced Technology Institute of Commuter-helicopter, Ltd. The calculated noise level showed good agreement with the measured data.