A RAY-ACOUSTICS APPROACH TO FUSELAGE SCATTERING OF ROTOR NOISE

A ray acoustics approach to fuselage scattering of rotor noise is considered based on a combination of classical geometrical acoustics and the paraxial ray approximation. The method can handle scattering by objects of arbitrary shapes and can be applied in an inhomogeneous moving medium. Applications to aeroacoustics include the scattering of blade vortex interaction (BVI) pulses by rigid objects. The BVI is modelled by a rotating impulsive point force. It has been found that the scattering effects of rotating sources cannot be ignored especially for sideline noise. Application to tilt-rotors has also shown the importance of the scattering effects by rectangular fuselages.