Influence of Scale Effect on Aerodynamic Performance Prediction of WIG Craft

There is a large error for aerodynamic performance prediction of the practice wing-in-ground effect (WIG) craft converted from the experimental results because the similarity criterion of Froude number(Fr) and Reynolds number(Re) cannot be guaranteed at the same time in the towing tank model test. This paper numerically studies the influence of scale effect on the aerodynamic performance of WIG craft. Three models of WIG craft with different scales (mean aerodynamic chord lengths from 0.52 m to 9.75 m) are selected to study the differences in aerodynamic lift, drag, and pitching moment coefficients for different angles of attack and ground clearances. The results show that with the increase in model size, the lift coefficient of WIG craft increases slightly, while the drag coefficient decreases significantly. The larger the scale is, the greater the pitching moment will be, the lager the slope of the pitching moment curve will be. The pressure and streamline distribution on the trailing edge of an airfoil are important reasons for the difference on different scales. Along with the increase of the scale of WIG craft model, the effect of increasing lift and reducing drag brought by ground effect is enhanced. To compensate for the aerodynamic performance prediction errors caused by scale effect during the takeoff and landing phase, effective measures must be adopted in tank tests.