Feedback Control of the Flutter of a Cantilevered Plate in an Axial Flow

We investigate the experimental control of the instabilities of a plate in an axial fluid flow. In absence of control, the plate is subjected to a flutter instability once a critical flow velocity is reached. In the present work, the objective of the feedback control is to increase the critical velocity and reduce the vibration amplitude once the flutter has appeared. Initially, the plate vibration and the action of the piezoelectric sensors is modelled in order to obtain a discrete state-space model of the controlled system. A Galerkin method is used, so that the discrete coordinates are the modal amplitudes of a beam when the flow velocity is zero. The action of the actuator is classically modeled as a momentum acting on the plate. To estimate the validity of the model, frequency response measurements are performed on the system. A good correspondence is found between the model and experiments. Dissipation coefficients are experimentally evaluated. Next, the feedback control loop design is investigated. As a first approach, a PI controller system is implemented. The controllability and stability limits of the closed loop system are investigated. We choose to implement experimentally this control, as it does not require an overly precise modelisation of the disturbances acting on the plate. Impulse response of the system without flow is performed to investigate the optimal control gain. Other tests are performed to show how the controller works against disturbances from a fluid flow. Despite the strong limitations that have been previously mentionned, some encouraging results have been found. The critical velocity is increased and the amplitude of vibration is lowered.