بررسي اثرات فركانس تقليل يافته روي گردابه هاي و نيروهاي آيروديناميكي وارد بر بالهاي مثلثي

Effects of Reduced Frequency on the Vortices and Aerodynamic Loads of Highly Swept Wings

The structure of the leading edge vortices over highly swept wings at various angles of attack has been studied. Some semi-empirical relations have been used to investigate the behavior of these vortices before and after burst. Further the normal force and drag coefficients and vortex burst location have been predicted for Delta wings with the sweep angles of 60 to 75 degrees for both static and dynamic cases. The results show that for dynamic motions, increasing the reduced frequency and oscillation amplitude and decreasing the wing sweep angle will increase the normal force and drag coefficients. The aerodynamic forces during upstroke motion are higher than their static counterparts. This phenomenon reverses during down stroke motion, creating the Hysteresis loop.