Pressure measurements of burst wakes over a three-element airfoil

Wakes generated by a three-element high-lift multielement airfoil system, consisting of a main element and two flaps, were studied using a 7-hole probe in a low-speed wind tunnel. Strong adverse pressure gradients applied to a wake can cause off-the-surface separation in the wake, which is known as wake bursting. The tests were performed in the University of Illinois low-speed low-turbulence subsonic wind tunnel on a multielement airfoil having a baseline-configuration chord length of 1.36 ft (0.416 m) and a model span of 2.8 ft (0.85 m). Results are presented at a freestream Reynolds number of 1×106 for a variety of configurations in which the flaps were positioned in different locations. An increase in wake thickness was observed with decreased gap size, increased overhang distance, and increased flap deflection angle. An increase in angle of attack caused a thicker wake, but essentially no change in the minimum velocity observed in the wake.