Effect of control surface on airfoil flutter in transonic flow

Based on aerodynamic identification technology in which unsteady CFD (computational fluid dynamics) is used, the unsteady aerodynamic reduced order models (ROM) are constructed. Coupled with structural equations, we get the analyzable models for transonic aeroelasticity in state-space. A Mach number flutter trend of a typical airfoil section with a control surface is analyzed and agrees well with that of CFD/CSD (computational structural dynamics) direct coupling method. Then we study the effect of the structural parameters (natural frequency and the flap static unbalance) of the control surface on the transonic flutter system. We find some classical structural design rules are unfavorable for transonic flutter problem. For transonic flutter problem, the flap rotating mode becomes the predominant mode of aeroelastic system. Classical technology of mass static balance or over-balance maybe reduces the stability of transonic aeroelasticity.