| With the rapid development of MEMS and low-power embedded technology,the applications of wireless sensor network(WSNs)have increased significantly.WSNs is composed of numerous static sensor nodes.Most of the nodes are arranged in remote and abominable terrain.Due to the energy reserve of traditional batteries is limited,which greatly affects the normal working time of the equipment,and cannot satisfy the functional requirements of WSNs.Therefore,in order to realize self-powered operation of electronic equipment,it is important to harvest energy from the environment,which have great theoretical value and practical significance.In this paper,based on the bluff body-cantilever wind-induced vibration piezoelectric energy harvesting device,the influence of the fin-shaped rods(FSR)symmetrically mounted on the cylindrical surface on the energy harvesting efficiency of the energy harvesting device is studied by experimental test and numerical simulation.The influence of the geometric characteristic parameters and installation angle of the FSR on the amplitude,frequency,aerodynamic force,wake vortex structure and energy harvesting of the cylindrical wind-induced vibration system are analyzed in detail.The investigation on the effect of FSR on cylindrical wind-induced vibration response and energy harvesting shows that:(1)The output voltage of piezoelectric wind-induced vibration energy harvesting device increases with the increase of load resistance.The output power increases at first and then decreases with the increase of load resistance.The optimum external load resistance of the energy harvesting device is200kΩ.(2)The flow separation point will be influenced by the installation angle of the FSR,and then affect the wake structure and aerodynamic force of the cylinder.According to the vibration response and energy harvesting characteristics of the cylinder,the installation angle of FSR is divided into three regions: 0°-70°(region I),70°-120°(region II)and 120°-150°(region III).The phenomena of galloping and vortex-induced vibration-of the cylinder were observed in the range of installation angle studied.When the wind speed is 6.80m/s,the installation angle of FSR is 50°,and the height is 0.20 D,the maximum amplitude,voltage and power of the FSR cylinder are 2.17 D,18.10 V and1.65 m W respectively.(3)After clarifying the influence of installation angle on vibration response and energy conversion characteristics,different FSR coverage angles in region I are studied,and it is found that the FSR with different coverage angles will also affect the position of the flow separation point,and then affect the vortex shedding.When the installation angle is 30°,the vortex shedding frequency increases with the increase of FSR coverage angle.The FSR with different coverage angle will affect the range of area I.When the FSR coverage angle is larger,the small installation angle will make the cylinder have a better vibration and energy harvesting characteristic,and when the FSR coverage angle is small,the large installation angle will make the cylinder have a better vibration and energy harvesting characteristic.When the installation angle of FSR is 60°,the height of FSR is 0.27 D and the coverage angle is 20°,the energy output characteristic of the device is the best,and the maximum voltage and power can reach19.70 V and 1.90 m W respectively.(4)Based on the research results of the influence of FSR installation angle and coverage angle on wind-induced vibration response and energy conversion characteristics,the effects of FSR with different heights on the performance of the device are further discussed.The results show that the height of the FSR will not affect the position of the separation point of the boundary layer,but the wake vortex shedding frequency and wake width of the cylinder will be affected.With the increase of FSR height,the amplitude and energy output of the cylinder first increase and then decrease.At the height of H=0.33 D,the vibration and energy conversion effect of the wind-induced vibration energy collection device is the best,and the maximum non-dimensional amplitude,voltage and power can reach 2.30 D,19.80 V and 1.96 m W,respectively.The investigation on the wind-induced vibration response and energy conversion characteristics of a cylinder with FSR shows that the passive control method can effectively improve the energy harvesting efficiency of the bluff body-cantilever wind-induced vibration piezoelectric energy harvesting device.The FSR can improve the energy harvesting efficiency of the energy harvesting device.When the FSR installation angle is located in the area I with better flow separation effect,the maximum output power can reach 1.96 m W,which can satisfy the power demand of micro sensor nodes.At the same time,the selection of FSR coverage angle should follow the following rules: select a small coverage angle when the installation angle is large,and a large coverage angle when the installation angle is small... |
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