Helicopter Rotor Noise Prediction Using ONERA and DLR Euler/ Kirchhoff Methods

Euler/Kirchhoff methods have been developed at ONERA and DLR to predict the High Speed Impulsive (HSI) noise generated by helicopter rotors in hover or in forward flight. The main purpose of this common work is to validate the aeroacoustic computations with delocalized test cases. In hover, the aerodynamic and acoustic results obtained by each partner are in good agreement with experiment. In forward flight, a first set of computations is performed with three different sized "classical" grids. For both partners, the pressure coefficients on the blade are in better correlation with experiment when the grid is refined. However, the capture of the shock waves propagation beyond the blade is not accurate enough to perform satisfactory Kirchhoff computations. The minimum pressure peak and the recompression slope of the acoustic pressure signatures are not accurately predicted, whatever the grid refinement of the Kirchhoff surface locations may be. An