Gurney Flaps on Slender and Nonslender Delta Wings

摘要

A parametric low-speed wind-tunnel study has been undertaken of the effects of Gurney flap height on thenaerodynamic characteristics of delta wings with sweep angles of 40, 60, and 70u0001n. Flap effects on lift and drag arenconsistent with previous two-dimensional data when wing geometry is accounted for by using the change in zero-liftnincidence rather than lift and using the relative flap area rather than flap height. Flap deployment primarily affectsnthe attached-flow potential lift on delta wings, with vortex lift being almost unchanged. Induced-drag factors arenconsiderably reduced as flap height is increased, but this is due to the use of flat-platemodels with near-zero leading-nedge suction. For control applications, pitch/lift ratios are similar to those for delta wings with conventional trailing-nedge flaps, but the trim-drag penalties are much higher. An aft shift in loading associated with Gurney flapndeployment leads to large aft movements of the aerodynamic center, which significantly reduces control capability.