The calculation of the pressure distribution on a thick cambered aerofoil at subsonic speeds including the effects of the boundary layer

Abstract

This Paper describes a method for calculating the pressure distribution on the surface of a two-dimensional aerofoil of arbitrary shape in subsonic flow, taking into account the presence of a boundary layer on the surface of the aerofoil. The effect of the boundary layer is accounted for by considering the inviscid flow over a displacement surface made up of the aerofoil section shape, boundary layer displacement thickness and. the wake. A simple model of the wake is introduced, and it is shown that provided certain simple conditions are satisfied in the region near the aerofoil trailing edge, the pressure distribution predicted is not unduly sensitive to the detailed development of the wake. The method has been developed using techniques which make it very suitable for computation on a digital computer. Calculations have been made of the pressure distribution on a RAR 101 aerofoil section at incidence for which measured boundary layer data were available, and also in the ease of a heavily cambered. aerofoil at incidence using theoretically predicted boundary layer characteristics. The comparison between the experimental. and predicted pressure distributions shows good agreement in both cases.