Experiment And Simulation Analysis Of A Flexible Piezoelectric Power Generation Device Based On The Karman Vortex Street Effect In The Flow Field

Because the marine environment is complex and variable,the low-power sensors that monitor the ocean parameters are not recycled after being placed,and the ordinary chemical batteries have limited volumes and cannot meet the long-term needs of the sensors.The marine environment contains a large amount of vibration energy.Therefore,it has become a hot spot of researchers in recent years that using the piezoelectric effect of the piezoelectric material to convert the huge vibration energy in the ocean current into electric power to charge the sensors.There are lots of vibration modes in the marine environment,but many are random vibrations.The Karman vortex street effect,as a common phenomenon in fluids,can stimulate the periodic vibration of flexible piezoelectric materials,which brings great convenience for the subsequent processing of electrical signals.Firstly,the distributed parametric model of the piezoelectric cantilever beam has been used to explain the vibration mechanism of the energy harvester.It is found that both the properties and the thickness of the substrate material have a certain influence on the power generation effect in the design of the harvester.Using wet mode analysis,the characteristics of the cantilever beam harvester wrapped by different fluid media have been further studied.It has been found that the density of the fluid medium can adjust the natural frequency and internal impedance of the harvester.Secondly,a numerical simulation model of single-layer grid has been established.By meshing the model,the grid parameters matching the model have been determined.Through simulation calculation,it has been found that the length and placement position of the rigid baffle have a significant influence on the frequency and vortex strength of the vortex shedding.These results can provide data and empirical support for the future research.Then the Fluid-Structure Interaction analysis model with a super-elastic single-layer grid has been established,and the feasibility of the model has been verified.It has been found by simulation that the vibration deformation of the elastic body is independent of the bluff body shape and only related to the characteristic length of the bluff body.Finally,a fluid-solid-electric three-field coupling model of a flexible piezoelectric energy harvester based on the vortex-induced vibration has been established to analyze the power generation at different placements behind the bluff body.The results show that the output voltage is the largest in case that the distance between the flexible piezoelectric harvester and the cylindrical bluff body is one time of the cylindrical diameter.Afterwards,the correctness of the analysis has been verified by the experiments in a water tank,which provides the support for the design of this kind energy harvester.