Parallel calculation of helicopter BVI noise by moving overlapped grid method

Abstract

This chapter summarizes the progress of a prediction method of helicopter blade-vortex interaction (BVI) noise developed under the cooperative research between National Aerospace Laboratory (NAL) and Advanced Technology Institute of Commuter-helicopter, Ltd. (ATIC). This prediction method consists of an unsteady Euler code using a moving overlapped grid method and an aeroacoustic code based on the Ffowcs Williams and Hawking (FW-H) formulation. The present large-scale calculations are performed on a vector parallel super computer, Numerical Wind Tunnel (NWT), in NAL. Therefore, a new algorithm of search and interpolation suitable for vector parallel computations is developed for the efficient exchange of flow solution between grids. The calculated aerodynamic and aeroacoustic results are in good agreement with the experimental data obtained by ATIC model rotor test at German Dutch Windtunnel (DNW). The distinct spikes in the waveform of BVI noise are successfully predicted by the present method.