Effects of 3-D Deformation of Elastic Wings on Aerodynamic Performance of an Aircraft Model

The wind tunnel experiment is conducted on a simplified aircraft model with rigid and two kinds of elastic wings to investigate the effect of wing 3-D deformation on the aircraft aerodynamic performance. The results show that two elastic wings exhibit different aerodynamic performances, which are classified as the lift-enhancement wing and the drag-reduction wing. For the lift-enhancement wing, the stall angle is delayed from 8° to 15° with a corresponding lift increment of 64.3% compared with the rigid wing. It is shown that the lift enhancement of the aircraft model is accompanied by the torsional vibration mode of the wing, which results in the significant improvement of wing circulation. For the drag-reduction wing, the aerodynamic performance is dominated by the time-averaged deformation, which couples the bending and twisting. The wing twist reduces the effective angle of attack, as well as the frontal area, and contributes to the decreased wake deficit. Meantime, the bent wings function as barriers to the cross flow resulting in a reduction of lift-induced drag. As a result, the drag coefficient is reduced from 0.115 to 0.098 with a reduction of 14.8% at angle of attack of 12°.