On the effects of oscillatory blowing on rapidly deflected flap

The flowfield transients of a NACA 0018 wing equipped with an array of oscillatory-blowing actuators executing rapid trailing-edge flap maneuvers are experimentally investigated in a water tunnel. The wing is held fixed, oriented at (formula presented) to present a prototypical attached, separated and massively-separated flowfield at a chord-based Reynolds number of (formula presented) . The wing spans the width of the test section to present a nominally two-dimensional flow and the flap length amounts to 25% of the total chord length. The oscillatory-blowing actuators are uniformly distributed across the wing span with exits located at the 70% chord-wise position, just prior to flap hinge. The resulting blowing frequency of a given actuator is (formula presented) with a momentum coefficient of (formula presented). In static wing tests it is revealed that the actuator array is capable of establishing flow reattachment. In rapid flap-deflection maneuvers it is shown that the addition of blowing actuation is cause for suppression of leading-edge shear roll-up that is characteristic of rapid flap deflection in the absence blowing. It is postulated that the combined effect of flap maneuvers and blowing may yield expanded bandwidth in applications of closed-loop control given the absence of significant transient formations and their associated time scales.