EFFECTS OF WING-TIP VORTICES ON LIFT OF T HE FLAT PLATES WITH LOW-ASPECT-RATIO

This paper describes the flow around flat plates with different aspect ratios using the method of flow visualization by hydrogen bubbles. Th e flow around plates was visualized over the central section and the l ower tip of the plates in a circulating water tank. At an attack angle smaller than the stall, the flow on the suction side of the central s ection separated at the leading edge, and then reattaching at the rear part of the plates. This phenomenon disappeared at angles larger than the stall. A series of spiral wing tip vortices was formed at the low er tip of the plates, which weakened at an angle larger than the stall . The maximum lift coefficient measured by this experiment was greater than that of the linear lift derived from the potential theory. The d ifference was greater at lower aspect ratios. This means that the lowe r the aspect ratio, the higher the effects of the wing tip vortex on t he lift of flat plates.