CANARD-WING INTERACTIONS IN SUBSONIC FLOW

Abstract

Extensive subsonic wind tunnel tests were conducted on a coplanar wing-canardconfiguration at various angles of attack. In these experiments, a 60° swept canard was placedupstream of a 60° swept main delta wing. This paper deals with the distribution of mean andfluctuating pressure coefficients on the upper surfaces of both the canard and the wing immersedin a variety of angles of attack. According to the results, presence of canard postpones the vortexformation and growth on the wing to higher angles of attack compared to the canard-off case. Dueto the canard downwash field, the wing operates at lower effective angles of attack and therefore,its vortex breakdown is delayed. The spectral analysis of the unsteady pressure on both the canardand the wing show the existence of narrow, dominant frequency band containing the majority ofthe fluctuation energy. This frequency band is believed to be the natural frequency of the leadingedge vortex. The results show that the dominant frequency of the wing vortex is lower than that ofthe canard having the same sweep angle as the wing, which is an indication of the wing vortexattenuation due to canard downwash field.