A Piezoelectric Energy Harvester Used for Underwater Propeller Detection

Inspired by the pressure rotation of turbine runner in water flow, a piezoelectric energy harvester used for underwater propeller detection is proposed in this paper. The flexible piezoelectric cantilever beam structure is placed inside the device. The propeller is driven by water flow to stimulate the cantilever beam to generate vibration. The piezoelectric plate on the cantilever beam collects vibration energy and stores it in the capacitor. According to the electromechanical coupling characteristics of the propeller piezoelectric energy harvester, a dynamic model of the system is established. The structure of energy collector is analyzed by finite element method. Modal analysis is used to determine the natural frequency of the structure and the influence of cantilever beam with different thickness on energy harvesting. The output power of piezoelectric plate and the optimum impedance of the device are measured experimentally at different speed of propeller. The optimum impedance is 100k Ω when the propeller speed is 120r/min. When the propeller speed is 300r/min, the output power of a single piezoelectric plate can reach 218µW.