Stall flutter suppression of NACA 0012 airfoil based on steady blowing

Abstract

Stall flutter is a classical aeroelastic phenomenon that seriously affects the performance of flexible wings at high angle of attack. In this article, steady blowing from the leading edge is designed to suppress stall flutter of a two-dimensional airfoil model at 15° static equilibrium angle of attack. The dynamic responses are measured to analyze the nonlinear characteristics of the aeroelastic system. It is found that the leading-edge blowing changes the local bifurcation behavior from a subcritical Hopf bifurcation followed by a saddle–node bifurcation to a supercritical Hopf bifurcation, with the flutter amplitude decreasing and the flutter critical velocity increasing. Time-resolved particle image velocimetry (TR-PIV) measurements are acquired to observe the flowfield evolution during stall flutter. The unsteady aerodynamic moment and flowfield results show that the leading-edge blowing effectively controls dynamic stall during oscillations. Low-momentum injection promotes shedding of dynamic stall vortices (DSVs) and reduces aerodynamic moment fluctuation, whereas high-momentum injection further suppresses the formation of DSVs and shrinks the aerodynamic moment hysteresis loop. During pitching-down of the airfoil, leading-edge blowing induces rapid recovery of the aerodynamic moment, which promotes the decay of stall flutter. When the blowing excitation is strong enough, stall flutter can be completely suppressed within several cycles.