HIGH-WAVENUMBER ACOUSTIC RADIATION FROM A THIN-WALLED SCARFED CYLINDER

The analysis of the radiation from an axisymmetric duct using the Geometrical Theory of Diffraction and uniform asymptotics, presented in a companion paper, is extended to an asymmetric, scarfed cylinder. The generic theory from the application to axisymmetric cylinders is briefly recapitulated and the geometrical calculations necessary for the analysis of the scarfed cylinder are presented in detail. The scarfed cylinder is used as a model for a novel technique of noise reduction in modern aeroengines in which the intake is directeda little upward to try and direct noise radiation away from the ground. We do not carry out a full parameter study, but preliminary results from this work suggest the technique has significant potential noise reduction benefits.