Energy Harvesting Using A Piezoelectric Cantilever Based On Cylindrical Vortex-induced Vibrationin Water

Karman vortex street is formed when the water flows over the non-streamlined body under certain condition. The piezoelectric beams can generate energy using the periodic pressure fluctuation. If the beams are fixed with one side of the non-streamlined body which is driven to move by the flow, it will vibrate continually with the non-streamlined body as long as the flow exists.In this paper, a double cylinders-piezoelectric beams energy harvester(double system) is put forward based on the vortex-induced vibration theory. The dynamic equation about the double system was established. The numerical analysis is fused with the ANSYS modal analysis and the experiment research to find the dynamic characters and the harvesting energy features about the system. the advantage of the system is embodied compared with the single cylinder – piezoelectric beam energy harvester. The main work of this paper is as follows:The energy equivalent method is used to solve the mass matrix, the damping matrix, the stiffness matrix, and the force matrix and the double system dynamic equation is built. The piezoelectric applied force is regarded as piezoelectric damping force which is fused with the damping matrix. The force applied by the flow is solved using the infinitesimal method. The point of the force is equivalent to the center of the cylinders.The modal analysis about the double system is conducted, to realize the resonance in the water. Numerical analysis is mixed with the modal analysis and the experiment result to obtain the vibrational features while the diameter of the cylinders is changed. The influence of the resonance changing with the length of the cylinders is also researched while some other parameters is invariant.The equation of the optimal resistor is built and is proved to be true by theoretical and experimental. The diameter and the velocity influencing on the optimal resistor is analyzed. The optimal modal design process is set up to optimize the double system under different flow velocities.The insulation problem is solved by coating silica gel under the water. The control variable method is used to compare the double system with the single cylinder-piezoelectric beam plant. And the advantage of harvesting energy is confirmed.