Numerical simulation of unsteady flow induced by a flat plate movingnear ground

Abstract

An aerodynamic model based on the general unsteady two-dimensional vortex-lattice method and the method of images was developed to predict the unsteady ground effect on the aerodynamic characteristics of a flat plate. The wake is computed as part of the solution by allowing it to deform and roll up into its natural force-free position. The model is not restricted by angle of attack, sink rate, and camber. The results agree perfectly with available exact (steady) solutions. It is also shown that the increase in the magnitude of C, and CM as a result of unsteady ground effect is greater for high sink rates, in a general agreement with published results. On the other hand, the effect of ground on wake shape and position is greater for lower sink rates. For large sink rates, the wake becomes very close to the flight path with its position less dependent on the height above the ground.