LEADING-EDGE VORTEX BREAKDOWN FOR WING PLANFORMS WITH THE SAME SLENDERNESS RATIO

A dye flow visualization investigation was conducted on two sets of wi ng planforms to better understand the effects of planform shaping on l eading-edge vortex breakdown. The first set of planforms consisted of rive cropped planforms, including a 66.3-deg delta, 80/55 double-delta , and three blended 80/55 double-deltas. The second set of planforms c onsisted of nine planforms of the same slenderness ratio, including a 69.3-deg delta, two gothics, three double-deltas, and three correspond ing blended double-deltas. Results of these experiments have indicated that planforms with a common slenderness ratio develop quite similar characteristics for breakdown of the apex vortex at the trailing edge. It was found that planform shaping significantly alters the forward p rogression of breakdown along the wing as angle of attack is increased . The effect of increasing filleting to double-delta planforms was sho wn to degrade the apex vortex breakdown characteristics of the planfor ms. Also, it was found that by moving the kink location of the double- delta aft on the planform, breakdown characteristics are improved.