Research On Fluid-induced Vibration Energy Harvester Based On Metasurface

With the development of wireless sensor networks,energy harvesting technology has been widely concerned.Wind energy is a kind of widespread clean energy.Traditional wind energy collection technology has the disadvantages of large volume,strong electromagnetic interference,which not suitable for application in sensor nodes in wireless sensor networks.The flow-induced vibration energy harvesting technology has many advantages,such as high efficiency,low electromagnetic interference and small size.A fluid-induced vibration energy harvester based on metasurfaces is proposed to improve the harvesting efficiency.The bluff bodys with three different type metasurfaces are introduced in the fluid induced vibration harvester,with the purposed to tune the fluid dynamic.Additionally,the natural frequency of the harvester is tuned by the furcation beams.The theoretical dynamical equations of the metasurface based fluid-induced vibration energy harvester are setup,and the solution of the above equations are solved.Three different type metasurfaces are designed,such as circular pit array,square pit array,and striped groove array.The aerodynamic characteristics of the cylindrical bluff body and square cylindrical bluff body with and without metasurfaces are discussed through numerical simulations.The influence of metasurfaces on the flow characteristics of the system is carried out.The branch beam is proposed in the above harvesters to realize tuning of the natural frequency,and the performance of the tuning method is carried out in finite element simulation.An experimental platform is built to verified the performance of the prosposed metasurface based fluid induced vibration harvester.The experimental platform consists of harvester prototype,a wind tunnel and measurent system.Preliminary experiments is carried out to verify the influence of metasurface and branch beams on energy harvesting efficiency.The peak output voltage and the root mean square voltage under different wind speeds and different resistance are measured seperatelly.For the cylindrical fluid-induced vibration energy harvester,when the wind speed is less than3m/s,the ordinary cylindrical fluid-induced vibration energy harvester has higher energy output.When the wind speed is greater than 3m/s,the output voltage of the energy harvester with circular concave metasurface is at least 32%higher than the ordinary energy harvester.When the wind speed is equal to 4m/s,the output voltage of the energy harvester with circular concave metasurface bluff body is 70.56%higher than the energy harvester with ordinary bluff body.The square bluff body inhibits the vibration of the system,and the output voltage is 59.12%lower than that of the ordinary bluff body when the wind speed is 2m/s.The output voltage of the striped bluff body is slightly different from that of the ordinary blunt body,the difference is less than22.7%,and the output voltage can be enhanced by 13.8%at most.The striped metasurface makes the output voltage of the system show a linear trend,and suppress the vibration of the system.The square concave metasurface can increase the output voltage when the wind speed is 3m/s and 4m/s.and shows the same variation trend as the ordinary energy harvester.For the square column fluid-induce vibration energy harvester,the circular concave metasurface and striped metasurface can stably improve the performance of the square column energy harvester and improve the energy harvesting efficiency.The metasurface of the square concave can improve the energy harvesting performance of the square column energy harvester at a certain wind speed,and make the system appear a potential well phenomenon at high wind speed.The output capacity increases with the wind speed,when the energy harvester is connected to the resistance load.The first turning point is appeared at 3 m/s wind speed with the resistance value is equal to 10~4Ω,which show an upward trend after 4m/s.The flow induced harvester with10~4Ωresistance has the best performance at the second turning point 5m/s,and an inflection point occurs at 6m/s.The vibration of the cantilever beam is inhibited and the energy output approaches0.In the range of test resistance value,the output voltage of the square bluff body and striped bluff body increases with the increase of load resistance,and the optimal output resistance is unavailable.The frequency tunning method of the furcation beam proposed in this paper is effective,and the the bluffy bodies with metasurfaces in the flow induced harvester can improve the energy harvesting efficiency,which provided a possible solution for energy harvesting of flow energy.