تاثير موقعيت عمودي كانارد بر ميدان سرعت روي بال مثلثي

Effects of vertical positions of canard on the velocity field on a delta wing

در اين نوشتار اثرات كانارد بر ميدان جريان روي بال و توزيع فشار آن به‌صورت تجربي مورد بررسي قرار گرفته است. كليه آزمايش‌ها بر روي تركيب بندي بال، كانارد و نيم‌بدنه و در دو حالت كانارد وسط و كانارد بالا به‌صورت چسبيده به جلوي بال در يك تونل بادِ مادون‌ِ صوت در ايران انجام گرفته است. نتايج به دست آمده نشان مي‌دهد كه حضور كانارد سبب قوي‌تر و پايدارتر‌شدن گردابه‌ي لبه‌ي حمله‌ي بال شده و آن را به سمت لبه‌ي حمله متمايل مي‌سازد. در زواياي حمله‌ي پايين انحراف كانارد، تاثير گردابه‌ي آن بر جريان روي بال بيشتر مي‌شود. همچنين در حالت كانارد وسط ادغام گردابه‌هاي كانارد و بال موجب تقويت بيشتر جريان گردابه‌ييِ تشكيل‌شده در روي بال مي‌‌شود.

A series of subsonic wind tunnel experiments were carried out to investigate the effects of the presence and vertical positions of a canard on the velocity field on 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. Our 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 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 towards upstream. The pressure loss induced by the canard vortex on the wing surface moves the wing vortex towards the leading edge. When the two vortices are placed at an appropriate distance from each other, their merging can lead to sudden pressure loss. In the mid canard configuration, canard and wing vortices merge at x/c > 0.5, and, as a result of this phenomenon, abrupt pressure loss occurs and more stable vortical flow is maintained on the wing. It is shown that low canard deflections, with respect to the wing or free stream, make significant changes to the flowfield over the wing.