Aeroacoustic validation of the free wake method first on the basis of a H145 main rotor in descent flight

To resolve aeroacoustic phenomena of helicopter rotors with CFD computations, very detailed, finely discretized, big and consequently expensive simulations setups are required. As the significance of the noise emission of helicopters is continuously increasing in terms of certification and regulation, a more efficient but also reliable and sufficiently accurate simulation method is mandatory. With today’s computational power free wake methods fulfill all of these attributes, as they can predict the main drivers of aeroacoustic noise emissions of rotors for the most certification relevant flight states correctly. Within the recent years at IAG the free wake method FIRST has been developed at IAG, which can be weakly coupled to flight mechanic tools such as CAMRAD II and (G)HOST. By means of a BVI forward descent flight state, FIRST is validated comparing the aerodynamic and aeroacoustic results to CFD computations and acoustic flight test data.