Study On Design And Performance Of Piezoelectric Vortex-Induced Vibration Energy Harvester In Agricultural Environment

The piezoelectric vibration energy harvester has the advantages of simple structure,high working stability,recyclable use,clean and pollution-free,etc.It is expected to become a substitute for ordinary chemical batteries in the near future,to provide power for various types of micro-electromechanical systems and ultra-low power wireless sensors.Aiming at the current piezoelectric vibration energy harvester has not been integrated into the actual application environment of agricultural engineering,and considering the complexity of the vibration source of the agricultural production environment,this paper mainly studies the technical issues that affect the output performance of piezoelectric vortex-induced vibration energy harvesters in agricultural environments.In this paper,the theory and simulation of the proposed piezoelectric vortex-induced vibration energy harvester in agricultural environment are comprehensively integrated with the knowledge of piezoelectric theory,mechanical vibration theory,structural mechanics theory and fluid mechanics theory.On the basis of theoretical and simulation analysis,the application feasibility of the piezoelectric vortex-induced vibration energy harvester in the agricultural environment under the wind environment of the fattening pig house was analyzed.And made the experimental structure of piezoelectric vortex-induced vibration energy harvester in agricultural environment,and carried out relevant experimental research on the factors that affect its output performance.The main research and conclusions are as follows:(1)Considering the characteristics of low vibration frequency and low flow rate in the agricultural environment,a piezoelectric energy harvester model was designed.By changing the structure size of the model,the simulation analysis and the conclusion were drawn:When designing piezoelectric energy harvester cantilever beam material,aluminum and iron materials can be considered;as the cantilever beam length increases,the output power decreases continuously;as the thickness of the cantilever beam increases,the output power gradually decreases;as the mass of the mass increases,the output power gradually increases.The modal frequency of the designed piezoelectric energy harvester is similar to the frequency of the vibration source in the agricultural environment,and the output power can meet the power consumption requirements of ultra-low power wireless sensors.(2)Using CFD to simulate and analyze the flow field of the fattening pigsty,the minimum flow velocity is reversed by the power required by the ultra-low power wireless sensor,and the calculated result is 0.688m/s.The result shows that there are more areas inside the fattening house in the vertical ventilation mode and the corridor area and the area above the pig penin of the pigsty,are more suitable for the application of piezoelectric vortex-induced vibration energy harvester.(3)The experimental structure of the piezoelectric vortex-induced vibration energy harvester was fabricated,and studied the influence of damping ratio ζ and the product m*ζ on the amplitude and output power of the energy harvester.The law is as follows:When m*>>1,the same mass ratio m*,the smaller damping ratioζ,the larger the normalized amplitude A*,the greater the maximum output power of the piezoelectric vortex-induced vibration energy harvester;the smaller m*ζ,the larger the normalized amplitude A*.The smaller the product m*ζ,the larger the maximum output power and the average value of the output power Wp.A smaller mass ratio m*and an appropriate damping ratio ζ can more effectively collect energy from the fluid.(4)Fabricated a cylindrical mass attached bump test structure,and studied the influence of the shape and position of the attachment protrusions on the amplitude and output power of the piezoelectric vortex-induced vibration energy harvester.When m*>>1,the attached cross-sectional shape of the cylindrical mass is a small tangent cylinder,which can effectively improve the amplitude and output power of the piezoelectric vortex-induced vibration energy harvester.When the horizontal angle of the cylindrical mass attached to the small tangent cylinder is 60 degrees,the starting velocity of vibration Low,and the phenomenon of vortex-induced vibration transforming into gallop occurs faster.(5)Designed and fabricated 4 sharp wedge rough element board test structures,the wedge rough element plates produced 4 kinds of turbulence of suitable size,and explored the influence of eddy current intensity on the amplitude and output power of the piezoelectric vortex-induced vibration energy harvester.When m*>>1,as the intensity of turbulence increased,the amplitude and output power at the same flow rate decreased.The intensity of turbulence will inhibit the output performance of the piezoelectric vortex-induced vibration energy harvester.