Stochastic aeroservoelastic analysis of a flapped airfoil

In order to increase the operability range of wings in terms of speed, the suppression of aeroelastic vibrations due to flutter phenomena using a trailing edge flap is analyzed. The aeroelastic modelling of a three degrees of freedom 3DOF airfoil in unsteady incompressible flow with pitch and control surface stiffness non-linearities is studied and an augmented state space representation is used for the time domain analysis of the problem. A V-stack piezoelectric actuator is used to move the trailing edge flap and its dynamic behavior is included in the analyses by means of a finite element model; the actuator input voltage saturation is also taken into account. A heuristic method, named Population Decline Swarm Optimization, is used for the tuning of the filtered PID controller parameters for different velocity values. The optimization algorithm is also used for the tuning of the Simple Adaptive Controller SAC invariant gains. A general uncertain state space modelling of the aero-servo-elastic plant is provided and used first for the open loop stochastic flutter analysis. Then, the stochastic robustness analysis is carried out to verify the robustness to structural, aerodynamic, and actuator parameters uncertainties of the proposed flutter suppression systems and to compare the gain scheduled PID approach with the SAC scheme.