Flow Field Analysis of Fully Coupled Computations of a Flexible Wing undergoing Stall Flutter

Fully coupled CFD-CSD simulations using HPCMP CREATETM-AV Kestrel were performed to compute the dynamic aeroelastic behavior of a torsionally flexible, finite aspect ratio NACA0018 wing. The uncontrolled dynamic instability resulted a very periodic limit cycle oscillation largely governed by the dynamic stall phenomenon. Three-dimensional effects due to the spanwise twist variation produces a localized stalled region which is bound by small interior angles of attack and the wing tip vortex outboard. The flow field at various phases throughout the limit cycle oscillation of the flowfield are shown to characterize the three dimensional flow structures. The coherence and development of a leading edge vortex is reduced due to the three-dimensionality of the problem. In addition to the uncontrolled case, the ability to suppress flutter through momentum addition through a blowing port at 75% span is detailed. By varying the amount of momentum addition added through a slot, varying control authority to suppress the aeroelastic instability is observed. In particular, two flow states are attained for depending on the magnitude of momentum addition.