Control of vortex-induced non-resonance vibration using piezo-ceramic actuators embedded in a structure

Closed-loop control of vortex-induced non-resonant vibration of a flexible square cylinder is experimentally investigated in this paper. Piezo-ceramic actuators were embedded inside the cylinder to cause an oscillation of the cylinder surface, which subsequently altered the fluid-structure interaction. Experiments were conducted in a wind tunnel at Reynolds numbers, Re, of 2800 and 8000. Two typical control schemes, i.e. Y_control and u+Y_control, were deployed using feedback signals from structural vibration Y and combined Y and fluctuating flow velocity u, respectively. The control effects on the structural vibration and flow were assessed using a laser vibrometer, an optical fiber Bragg grating sensor, hot wires and particle image velocimetry. Experimental results show that both vortex shedding from the cylinder and the vortex-induced non-resonant vibration were effectively suppressed. The best control effects were observed with u+Y_control in use; the root mean square values of Y, the structural strain rate εyalong the lift direction and u, i.e. Yrms, εy,rmsand urms, and the circulation Γ dropped at Re ≤ 8000 by 58%, 52%, 53% and 88%, respectively, compared with the unperturbed case. It was found that the control effectively modified the nature of the fluid-structure interaction by changing the in-phase fluid-structure synchronization at all dominant frequencies into anti-phase interaction, accounting for the suppression in both vortex shedding and structural vibration.