Calculations of the effect of blowing from the leading edges of a slender delta wing

Abstract

The thin-jet model, applied by Spence to the study of the jet flap, is combined with the vortex-sheet model, applied by Mangler and Smith to the study of leading-edge separation, to study the effect of blowing from the leading edges of a delta wing at incidence. A jet-vortex sheet, supporting a pressure difference related to the curvature of the streamlines in it, leaves the leading edge in a direction tangential to the wing plane and rolls up into a spiral above the wing. The inner part of the spiral is replaced by an asymptotic representation and the properties of this configuration are calculated by slender-body theory for the case of conical flow. The effects of the three basic parameters--the coefficient of blowing momentum, the initial angle between the jet streamlines and the leading edge and the ratio of the angle of incidence to the apex angle of the wing--are covered in the calculations. Blowing is shown to increase the lift on the wing and to increase the circulation about the vortex, while displacing it upwards and outboard. The limited comparisons which can be made with experimental results are encouraging.