Analysis of blade deformation effect on rotor BVI noise prediction

The acoustic field generated by helicopter main rotors experiencing blade-vortex interaction (BVI) is examined. The prediction tool starts from an aerodynamic solver based on a boundary integral formulation for the velocity potential, that is suited for configurations where wake/blade impingement occurs. It is fully 3D, can be applied to blades with arbitrary shape and motion and performs the calculation of both wake shape and blade pressure field. Then, an aeroacoustic tool based on the Ffowcs Williams and Hawkings equation is applied to evaluate the noise generated. The numerical investigation examines the sensitivity of the BVI noise predicted on the blade deformation included in the analysis. For helicopter rotors in descent flight, where severe BVI occurs, the effects of blade deformations are examined both in terms of local acoustic signatures and in terms of noise radiation characteristics.