Theoretical Research Of OWC Wave Energy Piezoelectric Generation Based On Vortex-Induced Frequency

It is one of the key technologies of current research to solve the problem of energy supply of sensor equipment for monitoring sea conditions in the far sea.The conversion of ocean wave energy into electrical energy can directly supply energy for the sensor.The form and structure of piezoelectric energy conversion are simple and suitable for small energy conversion devices,which can effectively solve the problems of ocean sensor long-time energy supply and information transmission.Wave have low excitation frequency and low power generation efficiency to driven piezoelectric generator.In this paper,a wave driven piezoelectric energy harvesting device based on vortex excitation frequency is proposed,It can convert low frequency wave energy into high frequency to induce air pressure on piezoelectric vibrators to realize energy conversion.The device is composed of three parts:OWC(oscillating water column)wave energy acquisition device,vortex exciter device and piezoelectric power generation device.Three-level energy conversion of wave energy,air kinetic energy and piezoelectric energy is realized.Mathematical modeling of OWC energy acquisition process is established based on fluid mechanics and linear wave theory.The effects of the size of the incident wave and OWC gas chamber on the conversion of wave energy into air kinetic energy are discussed.The conversion process of wave energy to air kinetic energy in OWC gas chamber is analyzed by numerical simulation.The simulation analysis results show that:when the incident wave period is 0.85s and the water draft of the front wall is 0.25m,the air velocity generated by wave energy conversion reaches the maximum value and increases with the incident wave amplitude.Based on Karman Vortex-induced effect,a vortex-induced frequency boost device is designed to convert the kinetic energy of the air in the OWC gas chamber into high-frequency excitation pressure,which serves as external excitation for the power generation of piezoelectric devices.When the wave period is 0.6s-1.1s,external excitation with a frequency of 55Hz-115Hz and a pressure of 35Pa-110Pa can be generated.According to the basic theory of mechanics,the deformation of cymbals piezoelectric vibrator is analyzed,and the tangential strain in the thickness direction of the piezoelectric vibrator,the tangential deformation at the lower end of the cymbals and the radial deformation of the piezoelectric vibrator are determined.Based on the fundamental theory of piezoelectric equation,the electromechanical coupling theory is modeled and analyzed.The results show that the output power of cymbal-type piezoelectric vibrator is related to external load and excitation frequency and increases with the increase of excitation frequency.In this paper,the numerical analysis and simulation are established for the OWC piezoelectric power generation utilization based on vortex excitation frequency about.The influences of wave period,wave amplitude,front wall draft depth,Strouhal number,airflow velocity,blunt body diameter,cymbal-type piezoelectric vibrator structure and piezoelectric vibrator material on piezoelectric energy generation it has discussed respectively.