عنوان مقاله [English]
A series of subsonic wind tunnel experiments were carried out to investigate effects of the presence and positions of a canard on the velocity field over a delta wing. In this research, flow field measurements on a one-meter aluminum alloy model are performed. In order to understand canard influence, the canard was set at two vertical positions, high and mid, with respect to the wing level. Flowfield measurements were performed to study the mechanism of canard-wing vortex interactions. The data show that canard vertical positions have a significant influence on the vortices locations, as well as on vortex breakdown. Results of the flow field measured by a specific rake show that the wing leading edge vortex becomes stronger by increasing The angle of attack. In addition, the vertical distance of the vortex, with respect to the wing surface, increases, and the position of the vortex breakdown moves upstream. The pressure loss induced by the canard vortex on the wing surface moves the wing vortex toward the leading edge. When the two vortices are placed at an appropriate distance from each other, their merging can lead to a sudden pressure loss. In the mid canard configuration case, both canard and wing vortices merge at x/c $succ$ 0.5, and, as a result of this phenomenon, abrupt pressure loss occurs and a stable vortical flow is maintained on the wing. It is shown that low alpha canard deflections, with respect to the wing or free stream, makes significant changes to the flowfield over the wing.