No abstract

A series of water-tunnel experiments were conducted to determine the effect of sinusoidal leading-edge protuberances on the aerodynamic characteristics of finite span wings. The models consisted of seven rectangular planform wings, two swept-leading-edge wings, and two wings with a planform resembling humpback-whale flippers. All models had an underlying NACA 63 4 -021 profile with protuberance amplitudes of 0.025-0.12 times the chord length. The models were examined at Reynolds numbers up to 4.5 × 10 5 and angles of attack up to 30 deg. The lift and drag coefficients were nearly independent of Reynolds numbers above 3.6 × 10 5 . Specific rectangular-planform models had appreciably greater lift coefficients over a limited angle-of-attack range when compared to the baseline model. However, with the exception of the planform that resembled the humpback-whale flipper, the lift-to-drag ratio of all leading-edge modified models was comparable to or less than the equivalent baseline model. The flipper model had a slightly smaller drag coefficient than its baseline counterpart from 17 to 21 deg. The drag of all other models examined was equal to or greater than the corresponding baseline for the entire angle-of-attack range examined. The presence of leading-edge protuberances reduced the span efficiency of the rectangular-planform wings when compared to the baseline, and the primary parameter affecting the span efficiency was the protuberance amplitude.

No abstract

No abstract

No abstract