Fan Noise Propagation within Curved Bypass Ducts with 3D Features

This paper focuses on aft radiated fan noise propagating through the bypass duct: the effect of duct geometry on noise propagation is examined. The acoustic benefits of a novel highly curved bypass geometry are compared with those of a typical modern turbofan engine bypass geometry. Both 2D and 3D finite element models are used to examine the effect of duct geometry and other features on noise propagation, including modal scattering within the duct. An analytic radiation model is also used to examine the effect of these features on sound directivity patterns in the far-field.