Hydrodynamical Forces on a Moving Body in Ground Effect

Abstract

An experimental technique is developed for a vehicle moving steadily in the vicinity of the ground. The towing tank with a steadily advancing carriage is used and the unfavorable effects of the boundary layer on the wall of wind tunnel is fully removed. Experiments with a box-shaped model and a car model revealed some interesting features of lift, drag and side force at various clearance from the ground. Lift force is more sensitive to the boundary layer and it should not be measured in a wind tunnel. The flow with vortices near the bottom surface of the body gives one of the most important effects on the forces.