Progress Report on Observations of Three-Dimensional Flow Patterns obtained during Stall Development on Aerofoils, and on the Problem of Measuring Two-Dimensional Characteristics

Abstract

Surface oil-flow patterns were used at low speeds on both thick and thin aerofoils to show the onset of three-dimensionality in either separation or re-attachment when there is an appreciable extent of the separated flow that accompanies the development of the stall. Observations on a thick aerofoil in compressible flow showed a similar trend in the re-attachment behind a shock-induced separation. A form of boundary layer control applied at the corners at the ends of the aerofoil was able to prevent separation of the corner flow but not to inhibit the development of three-dimensionality.