F low Field Over a Non- Experimental Investigation of The Slender lambda Shaped Wing by Pressure Measurement

The flow fields over a non-slender lambda shaped wing including vortex formation and the effect of angle of attack on structure, strength and location of the vortices were investigated in a closed circuit low speed wind tunnel by pressure measurement. The tests were conducted at velocity of 20 m/s and different angles of attack from 5 to 20 degrees. The Reynolds number of the model was about 2×105 according to the root chord. The results showed three vortical flows were formed over the wing surface. The first vortex was the apex vortex; the second one was generated before the leading edge crank and strengthened after the crank and the third one was formed after the leading edge crank. By increasing the angle of attack the vortices became larger and stronger and closer to the wing root. At a specific angle of attack the structure of the vortices was changed rapidly and the vortex break down was occurred. The location of vortex break down moved toward the wing apex by increasing the angle of attack.