Scale effect on wave planing performance of amphibious aircraft at constant speed

Abstract

Scaled model testing is commonly recognized as a valuable approach for predicting aircraft performance in the aeronautical applications. However, challenges arise in the case of wave planing events for amphibious aircraft due to difficulties in satisfying the scaling laws of Reynolds number and Froude number simultaneously in a water tank. Therefore, it is important to evaluate the scale effect of regular wave planing process for amphibious aircraft. In this study, by fixing the Froude number, five geosim cases with different scale factors (1/1, 1/2, 1/4, 1/8 and 1/16) are carried out based on the Reynolds-Averaged Navier–Stokes equations (RANS) framework. The hydrodynamic and aerodynamic characteristics at different scales are respectively examined in detail through several physical results, including acceleration, pressure, shear force, velocity and free surface elevation. Comparative analyses among all scaled models reveal that the aerodynamic and hydrodynamic performance both monotonously change with the scale factor, yet the proportion of aerodynamic and hydrodynamic loads remains within a reasonably small range. Furthermore, the results indicate that the scale effect primarily stems from the lack of similarity in Reynolds number, thus resulting in the discrepancies of boundary layer, wave surface elevation and flow separation between the scale model and prototype.