Numerical Investigation on Aerodynamic Characteristics of a Compound Wing-in-Ground Effect

The performance of a wing-in-ground effect craft depends mostly on its wing configuration. The aerodynamic characteristics of compound wings were numerically investigated during the ground effect. The compound wing was divided into three parts with one rectangular wing in the middle and two reverse taper wings with anhedral angle at the sides. The NACA 6409 airfoil was employed as a section of wings. Three-dimensional computational fluid dynamics was applied as a computational scheme. The k-turbulent model was used for the turbulent ?ow over wing surface. The computational results of a rectangular wing with aspect ratio 1, angle of attack 2 deg, and different ground clearance were compared with the experimental data of other published work. Next, the principal aerodynamic characters of compound wings and a rectangular wing were computed for various ground clearance. The aerodynamic characters of compound wings were compared with the rectangular wing, which has an acceptable increase in lift and decrease in drag. Consequently, the lift-to-drag ratio has a considerable improvement especially in small ground clearance, although their nose-down pitching moment has a little reduction. The performance of the wing improves noticeably for a certain total span of compound wing when the span of the middle part becomes smaller.