Feather-inspired Flow Control Devices: 2D vs 3D Comparison*

Birds are superior in terms of agility and maneuverability compared to small-scale UAVs, partly because birds’ wings are equipped with multiple flow control devices. One of such flow control devices is a group of feathers known as the coverts. The coverts are passive high-lift aeroelastic flow control devices used by birds to mitigate stall and control flow separation. Prior studies by the authors have investigated the performance characteristics and physics of torsionally hinged covert-inspired flaps mounted on the suction side of airfoils in 2D settings across different Reynolds numbers. In this work, we present wind tunnel experiments using time-resolved PIV flow measurements and force data at Reynolds number O(10⁵) to investigate the effect of covert-inspired flaps on a 3D wing section. We will examine the fluid-structure interaction mechanisms for the 3D system and compare them to our prior findings for the 2D system. Results will show the effects of the spanwise flow, due to the wingtip vortices, on the aerodynamic performance of the wing-flap system and quantify how the deployment dynamics of the torsionally-hinged covert-inspired flaps change between the 2D and 3D cases.