A DOUBLET-LATTICE METHOD FOR CALCULATING LIFT DISTRIBUTIONS ON OSCILLATING SURFACES IN SUBSONIC FLOWS

Approximate solutions from the linearized formulation are obtained by idealizing the surface as a set of lifting elements which are short line segments of acceleration-potential doub? lets. The normal velocity induced by an element of unit strength is given by an integral of the subsonic kernel function. The load on each element is determined by satisfying normal velocity boundary conditions at a set of points oil the surface. It is seen a posteriori that the lifting elements and collocation stations can be located such that the Kutta condition is satisfied. The method obviates the prescription of singularities in lift, distribution along lines where normal velocity is discontinuous, and is readily adapted for problems of complex geometries. Results compare closely with those from methods that prescribe lifting pressure modal series, and from pressure measurements. The technique constitutes an extension of a method developed by S. G. Hedman for steady flow. © 1969 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.