Experimental Investigation of Single Wing Stall Flutter

Abstract

Flutter of aircraft wings or turbomachinary bladings occurs when the flow is separated from the suction surface ofthe profile during all or part of the cycle of oscillation. Due to the adverse pressure gradient, the separation of the boundary layer that is confined to a thin layer causes the so called airfoil stall. The unsteady nature of the flow separation from the airfoil surface causes the unsteadiness of the stall phenomenon. This stall . in turns causes the aerodynamic forces, such as the lift and the moment, to change with certain frequency. Tllis dynamic behavior of the aerodynanlic forces tends to vibrate the structure of the airfoil element. The entrainment of the natural frequency with the aerodynamic frequency makes the airfoil to experience self vibratory motion which is called.flutter.

The present study is for a two-dimensional characteristic airfoil section with a two degrees of freedom in bending and torsion. Tile airfoil freely moving inside the test section which is mom1ted on a subsonic air speed wind tum1el. Two sides special mechanisms are designed to