Aerodynamically Adaptive Control of a Flexible 3-D Wing using Distributed Bleed Actuation

The aerodynamic loads effected by controlled interactions between a flexible cantilevered 3-D wing model and the embedding cross flow are explored in wind tunnel investigations to effect tunable structural and aeroelastic characteristics. The aerodynamic loads are regulated using distributed air bleed driven by flow induced pressure difference between the wing’s pressure and suction sides through clusters of surface ports and the bleed flow rate is dynamically regulated using activated louvers on the suction side. The effectiveness of the induced loads is demonstrated by forcing time-periodic cross-stream bending vibrations of the wing using bleed actuation near its tip, while inboard bleed actuation is used independently to mitigate the forced vibrations using a limited-state feedback proportional controller of the wingtip motion that achieves a 70% reduction in the RMS of tip motion. High speed stereo PIV measurement in the spanwise cross-stream (y-z) plane in the wing’s near wake are used to measure the unsteady changes in spanwise distributions of streamwise vorticity concentrations and reveal the effect of bleed actuation on the spanwise load distribution through unsteady changes in sectional circulation. These measurements demonstrate how the actuation leads to forcing and control of the wing’s time-dependent bending motion. The effect of the bleed actuation on the apparent structural properties of the wing are assessed and demonstrate significant changes in damping in the presence of vibration control.