Effect of Canards on Delta Wing Vortex Breakdown During Dynamic Pitching

Abstract

The effect of a canard on delta wing vortices was investigated in the 2 3 3 ft water tunnel at Wichita State University. It is well known that the leading-edge vortices generated by a delta-shaped wing greatly enhance a vehicle’ s performance at high angles of attack. In this experiment, different canards were placed in front of a 70-deg swept main delta wing. Dye e ow visualization was used to observe the vortex breakdown location during dynamic pitch-up and pitch-down motion with varying pitch rates. Compared to the no-canard cone guration, results showed that there was a delay in vortex breakdown because of the presence of the canard and the dynamic pitch motion. The most favorable delay was obtained when the canard was located closest to the main delta wing and the model was pitched up at a fast rate or pitched down at a slow rate. Complete vortex breakdown on the main delta wing (i.e., full stall ) occurred at 53 deg for the static case without canard. In comparison, complete vortex breakdown occurred past 90 deg when a canard cone gured delta wing was pitched up at the fastest rate tested (i.e., k = 0.2).