Research On Integrated Piezoelectric Wind Energy Harvesting System Based On Compound Flow-Induced Vibration

Today,as engineering projects become increasingly intelligent,wireless sensors,micro-energy and MEMS are widely used in engineering detection and monitoring.It is a feasible way to solve the energy source problem of low-power wireless sensors in natural environment to collect mechanical energy of flow field by piezoelectric collecting device.At present,most piezoelectric collecting devices used in natural wind energy collection only collect one kind of mechanical energy induced by wind vibration.In this paper,based on the characteristics of vortex-induced vibration and impulsive vibration wind energy collection devices,a composite flux-induced vibration piezoelectric wind energy collection device is designed.In this paper,combined with the typical vortex-excitation and galloping theory,a piezoelectric wind energy collecting structure with compound fluid-induced vibration is designed.In this structure,by adjusting the size and aerodynamic shape of the resistance fluid in the structure,galloping can be achieved and stable vortex streets can be formed at the same time,so as to improve the energy collection capacity of the VIV piezoelectric collection device.The vortex-induced vibration(VIV)collecting piezoelectric element mounted on the resistive fluid can enhance the galloping effect of the resistive fluid when the element is subjected to VIV.Through simulation and energy collection experiments,the action relationship between vortex induced vibration and galloping vibration in the device is studied and verified.The research contents of this paper are as follows:Firstly,the positive excitation of vortex-induced vibration is verified by two-dimensional flow field simulation.The vortex-induced force and galloping aerodynamic force were estimated,and the fluid-structure interaction simulation was simplified into solid mechanics simulation.It is found by finite element software that the coupling of galloping vibration and VIV enhances the response and output capacity of single vibration.Through the simulation of the bionic piezoelectric element with different shapes,it is found that the influence of the bionic piezoelectric element on the collection of galloping energy is also different.The aerodynamic characteristics of two vibration energy collection structures were studied by adjusting the layout position.Wind tunnel experiments using the output voltage as the energy collection performance index of the device show that the coupling of Vortex-induced vibration and galloping vibration improves the collection capacity of a single vibration,and the energy collection capacity of the wind energy collection system depends on the coupling effect of gallop vibration and vortex induced vibration.When the system adopts "Lilac leaf" configuration,its output voltage root mean square value is the largest,but when the system adopts "Ginkgo leaf" configuration as piezoelectric collecting unit,the output open circuit voltage amplitude is the largest.By measuring the output power of the external 2MΩ resistance system,it is found that the system output power and power density are the highest when the piezoelectric wind energy collecting unit of "Ginkgo leaf" configuration is adopted,the output power is 9.463μW,and the power density is 15.768μW/cm3.The experimental results show that adjusting the wind deflection Angle and wind direction Angle of the resistive fluid and the bionic piezoelectric blade will affect the vortex street state and reduce the amplitude of vortex-induced vibration,but the output range of the system will be improved by adjusting the wind direction Angle.Because the position of the bionic piezoelectric blade under load in vortex street is changed,the amplitude range of the bionic piezoelectric blade increases under different wind speeds compared with the prototype position.