Flutter suppression of airfoil with control surface using a variable-throttle hydraulic system under extreme fault condition

In this study, a damping system consisting of a variable-throttle hydraulic system was designed for flutter suppression of a control surface under extreme fault condition. A mathematical model of an air foil with a control surface connected to an actuator in the damping mode was established. Flutter velocities were calculated using the Runge–Kutta method. The damping forces of the damping system consisting of a variable-throttle system and fixed orifice were compared at the same flutter velocities, which should be overcome by the control surface under normal condition. The effects of the main parameters of the variable-throttle system on the flutter velocity and damping force were analyzed. Finally, an experiment is conducted to verify the validity of the variable-throttle system model. The results show that flutter velocity of airfoil with control surface under extreme fault condition can be enhanced from 11.88 to 25.02 m/s due to the damping system and the damping force of variable-throttle system is significantly smaller than that of fixed orifice under normal condition, especially at high velocities of actuator. The variable-throttle hydraulic system has been applied to aircraft and can possibly be extended to other mechanical equipment field.