Simulation And Experimental Study On Underwater Piezoelectric Energy Harvesting Based On Fluid Induced Vibration

In recent years,As the energy crisis becomes more and more serious,the rapid development of MEMS and micro-sensors,make use of piezoelectric effect to absorb energy from natural has attracted more and more attention of scholars.In this paper,an underwater piezoelectric energy harvester based on flowinduced vibration of water is introduced.The energy harvester is composed of a cylinder and a piezoelectric cantilever beam.Firstly,a mathematical model for underwater vibration of a single energy harvester was established.Without changing the piezoelectric cantilever beam,the effect of the cylinder mass ratio and the diameter on the energy harvester is studied numerically and experimentally at a flow speed of 0.1-0.65 m/s.It is found that the smaller the cylinder mass ratio,the higher the energy output of the energy harvester,and the higher the initial vibrating flow speed;Increasing the cylinder diameter,the flow speed range of high output will become larger,but not increase the start-up flow speed.At the point of the peak output voltage,there is an optimum cylindrical diameter,which is close to the width of the piezoelectric beam.Then two piezoelectric energy harvesters are used as a group,and the same group of energy harvester parameters are set to be the same,harvesters were divided into four groups according to the cylinder mass ratio and diameter.Two energy harvesters in the same group were Serial discharged underwater.At the same flow speed range as single harvester,the open-circuit output voltage of two energy harvesters is simulated and experimentally studied when the center-tocenter distance is different.It is found that regardless of the center distance,the maximum output of the behind energy harvester is always not less than the previous energy harvester,the output of both energy harvesters is not weaker than the single energy harvester,and there is an effect of increasing the output flow speed range.The output of the two energy harvester has been greatly improved at the small center distance.In particular,the behind energy harvester output is much larger than the single energy harvester with the same parameter.Compared with a single energy harvester,it's output can increase by 103%.Moreover,the output still has room for improvement.For The energy harvesters with the same cylindrical diameter their output changes with the center distance is similarly.changing cylindrical parameters affect the mutual influence intensity of the two energy harvesters,and thus affect the output increase rate.The research provides theoretical and experimental guidance for underwater piezoelectric energy harvesting based on flow induced vibration,and has important significance for improving the output characteristics of piezoelectric energy harvester.