Pressure Distributions on Wing Surface and Aerodynamic Properties of 3-D Wings Cruising in the Ground Effect

Abstract

When the wings fly near the ground/water surface, a phenomenon so called ‘ground effect’ appears in which the liftto-drag ratio drastically improved. Although a numerous studies focused on the ground effect have been presented so far, there are less experimental results of pressure distribution on the surface of 3-D wings in the ground effect. In this study, authors develop a measurement system using the wind tunnel to measure both pressure distributions on the wing surface and aerodynamic forces at the same time, and carry out the wind tunnel test for a rectangular wing and a main wing with end-plates which is a part of a canard-configuration WIG designed by the authors. Wing models are accurately manufactured by using the 3-D printer and the NC machine so that the pressures at 126 points on the wing surface are measured together with aerodynamic forces. Experiments are performed not only for the cruising condition but also for the heeling condition and measured results are compared with the theoretical calculation results. It is confirmed that the theoretical calculations in cruising condition show good agreements with measured pressure and aerodynamic forces. Additionally, it is suggested that the measured asymmetric aerodynamic forces in heeling condition may contain the forces acting on the strut, which is induced by the aerodynamic interaction effect between the wing models and the strut.