Effects of canard oscillations on the unsteady flowfield over the wing in supersonic flow

Abstract

Few studies have been devoted to effects of canard oscillations on the flowfield over the wing in supersonic flow and the associated time lags. In this article, an in-depth experimental study on a closely coupled canard-wing-body configuration in supersonic flow has been undertaken to mark the zone of influence of the oscillatory canard on the wing. Surface pressure measurements have been performed on the wing downstream of canard in both static and oscillatory cases at various wing angles of attack and canard deflection angles as well as the canard oscillation amplitudes and frequencies. The results show that the upwash and downwash flowfields due to an oscillatory canard periodically change the effective angle of attack seen by the wing and have different effects on various regions. In supersonic flow, the pressure rise due to the oblique shock waves causes the primary flow separation and the vortex break down onsets to occur at higher angles of attack, comparing to those in the lower speed regimes. According to the results, the mid-span region on the wing, which is directly in the shadow of the oscillating canard, receives more disturbances. During upstroke, the canard induces a downwash field to the front half of the wing, while in downstroke motion, the front regions of the wing experience upwash flow, giving rise to the effective angle of attack seen by the wing. Among various oscillation parameters, the pitching amplitude was observed to have a strong impact on the time lag in flowfield over the wing.