Wing kinematic measurements and reconstruction
SPIV measurements of the flow field associated with stall flutter on the flexible wing

In order to enhance aircraft efficiency designers are increasingly utilizing lightweight, high aspect ratio wing designs. This is because lower weight means less energy is required to keep the aircraft aloft and high aspect ratio wings have lower induced drag. These two factors combine to enable high efficiency vehicles. These wing designs appear in applications from electric and H.A.L.E. vehicles, to wind turbines and commercial aircraft. Unfortunately, lightweight, high aspect ratio wings are also inherently more flexible and therefore more susceptible to adverse fluid structure interactions (FSI) that can lead to large deformations, formation of aeroelastic instabilities and ultimately structural failure. If these large deformations cause flow separation, the wing can develop into a stall flutter mode which can either stabilize into a limit cycle oscillation (LCO) that fatigues the wing and reduces overall life, or diverge and result in catastrophic failure of the wing structure.  

In an effort to enhance vehicle performance by allowing for utilization of lightweight, high aspect ratio wings and ensure survivability by mitigating undesirable aeroelastic instabilities, this research project has been initiated, focusing on the suppression of stall flutter and more generally, aeroelastic instability in lightweight, high aspect ratio wings. To accomplish this goal, an understanding of how the unsteady aerodynamics and structural kinematics of the fluttering wing couple to produce stall flutter in a fully deformable, three dimensional wing is developed using a cyber-physical wing model. The fluid dynamics of the model are analyzed through phase locked stereoscopic particle image velocimetry while the structural kinematics are captured through stereoscopic surface motion tracking.  To suppress the instability, different active flow control devices are examined and utilized.