Assessment of computational tools for the prediction of BVI noise

The paper presents an assessment of various computational tools pertinent to the prediction of rotor blade induced noise developed by the partners of the Friendcopter project entitled "Integration of Technologies in Support of a Passenger and Environmentally Friendly Helicopter". The computational tools comprise of coupled aeroelasticity and aerodynamic analysis tools, which provide input to the aeroacoustic codes used for predicting the helicopter footprints and noise levels. As these computational tools will be employed during the design phase of future environmentally friendly helicopters, assessment of their accuracy is required. In the nineties the HELISHAPE consortium embarked into a European research programme on rotorcraft aerodynamics and acoustics conducting a parametric model rotor test. These results have been reported in previous European projects (EROS, ROSAA). The test cases are based on two modern rotors designed by Eurocopter, the EC/ONERA 7A and 7AD, which differ only by their blade tip shape: the 7A has a rectangular blade tip while the 7AD has the SSP8 parabolic tip with taper. The choice of these experimental cases seemed to be the most appropriate ones for assessing the present computational tools. In the paper, we describe the various aeroacoustic methods employed and present a comparative analysis and assessment of the predictive results from these.