Investigations of the Rolling-Up of the Vortex Wake and Calculation of Non-Linear Aerodynamic Characteristics of wings.

This report investigates the rolling-up of vortices over and behind wings of low and high aspect ratios, and simultaneously the evaluation of the aerodynamic characteristics including the spanwise and chordwise pressure distributions on the wings. The present method is based on the extension of the Vortex Lattice concepts also to low aspect ratio wings and the rolled-up vortex which is established over as well as behind the wings. The computer program, which was developed, is capable of reproducing the results of the Vortex Lattice Method (VLM) for linear aerodynamic coefficients for high aspect ratio wings. The wake effect is included in the modified VLM program. This wake calculation showed that the center of the tip vortex is very near the wings' tip for the high aspect ratios wings. The non-linear aerodynamic characteristics are evaluated when the vortices are shed over the wing and begin the rolling-up process from the leading edges. This effect is particularly important for wings of low aspect ratios.