A Surface Vorticity Theory for Propeller Ducts and Turbofan Engine Cowls in Non-Axisymmetric Incompressible Flow

Abstract

Starting from the basic Fredholm integral equations, a surface vorticity theory is developed for the prediction of annular aerofoil performance in three-dimensional flow. A mathematical model is proposed for the general case of the axisymmetric body in non-axisymmetric flow, using a Fourier series to represent circumferential variations in bound vorticity strength. Using the pure incidence case as an example, it is indicated how an economical solution of the flow may be arrived at by use of a digital computer. The theoretical pressure distributions obtained are compared with the results of wind-tunnel tests on an annular aerofoil model.