Active control method on flutter suppression of a high-aspect-ratio two-dimensional airfoil with a control surface

The structure of aircraft´s airfoil is elastic and flexible. When the aircraft flies at a certain speed in the flow field, the couple-interaction of airfoil´s elastic deformation and aerodynamic force will cause its self-excited vibration with amplitude increase, and this phenomenon is called airfoil´s flutter. Such sharply divergent structural aeroelastic vibrations may threaten the flight safety seriously. This paper focuses on the problem of active flutter suppression of a typical high-aspect-ratio two-dimensional airfoil with a control surface. The control surface is driven by an actuator. First, a physical model of the high-aspect-ratio two-dimensional airfoil involving a three-DOF (degree-of-freedom) motion which includes the dynamic characteristics of the actuator is proposed. By analyzing the physical model´s differential equations of motion and the actuator´s transfer function, the state-space of the aeroelastic system which is composed of the high-aspect-ratio two-dimensional airfoil and the control surface with actuator is established. Then, on the basis of the state-space model, controllers respectively based on the optimal control theory and robust control theory are successfully designed. Finally, the simulation results indicate that all these designed controllers have an excellent performance on flutter suppression and they also can be able to improve the original system´s flutter boundary speed. The contrastive analysis of controllers designed by different methods is also given at the end of this paper.