Leading-Edge Slat Design by a Semi-Inverse Technique

Abstract

A method of generating high-lift leading-edge slats for arbitrary airfoils is developed. The technique assumes that a desirable pressure distribution for the main airfoil is specified from boundary-layer considerations. Using conformal transformations, slats which generate pressure distributions having a least squares matching to the specified distribution are developed. The approximate slat chord, position, and thickness are selected, and the semi-inverse solution then generates the slat camber distribution required to achieve the desired modulation. Accurate matchings to the specified pressure distributions are achieved for the elliptical airfoil test cases. Predicted pressure distributions on the airfoil and on the slat generated by the semi-inverse solution compare well with pressures computed by a direct numerical solution. Small, thin, highly cambered slats located close to the airfoil nose are found to be desirable. As a design tool, the method rapidly develops a family of slats which will induce the desired modulation on the airfoil.