UNSTEADY STALL CONTROL USING DYNAMICALLY DEFORMING AIRFOILS

An experiment documenting the compressible flow over a dynamically def orming airfoil is presented. This airfoil, which has a leading edge ra dius that can be dynamically changed, was tested at various deformatio n rates for fixed airfoil angle of attack. Selected leading-edge shape s were also tested during airfoil oscillation. These tests show that f or a range of Mach numbers observed on the retreating blades of helico pter rotors the dynamic stall vortex can be avoided by a judicious var iation of leading-edge curvature.