Influence of endplate on aerodynamic characteristics of low-aspect-ratio wing in ground-effect

摘要

A numerical analysis is performed to investigate the aerodynamic characteristics and static height stability of the endplate on aspect-ratio-one wing in ground effect. The investigation is carried out on angles of attack from 0° to 10° and ground clearances at a trailing edge from 5% of chord to 50%. The analysis shows that the ground effect increases the lift by high pressure on the lower surface, reduces the induced drag, increases the suction on the upper surface, and consequently considerably enhances the lift-drag ratio. The endplate, which prevents the high-pressure air escaping from the air cushion and reduces the influence of wing-tip vortex, augments lift and lift-drag ratio further. Interestingly, the drag with the endplate does not increase as much as the lift does when the airfoil is brought close to the ground. From the analysis and visualization of computation results with the endplate, it is found that two wing-tip vortices are generated from each wing surface, their strengths are stronger, diminished rapidly and the influence of the wing-tip vortices are decreased. The outward drift of wing-tip vortex, which is generated from the lower wing surface, is observed. Irodov's criteria are also numerically evaluated to investigate the static height stability of wings with and without the endplate. The comparison of Irodov's criteria shows that the endplate is not favorable for static height stability but reduces the deviation of the static height stability with respect to pitch angles and heights.