可变形式翼型钝体的风致振压电俘能器

Wind-induced vibration piezoelectric energy harvester with a deformable airfoil-shape blunt body

针对现有风致振压电俘能器工作风速范围窄、高风速下振幅过大等问题,提出一种可变形式翼型钝体的风致振压电俘能器,主要由可变形式翼型钝体、悬臂梁以及压电组合梁构成,钝体的弹性翼受风力影响产生形变,从而实现系统振动特性的自我调节,以期提高俘能器的环境适应性。建立了俘能器的COMSOL有限元模型,通过仿真与试验分析了风速对其钝体形状及振动特性的影响,并获得了迎风角和弹性翼厚对俘能器输出性能的影响规律。结果表明:选取迎风角120°和弹性翼厚0.15 mm时俘能器的工作风速范围达到21 m/s,且当风速小于8 m/s时,弹性翼变形较小,系统以驰振为主,输出电压随风速增加而增大;当风速在8~17 m/s时,弹性翼形变量进一步增大,系统由驰振逐渐向涡振转变,输出电压变化较小;当风速在17~25 m/s时,钝体因弹性翼变形过大呈弯弧状,系统以涡振为主,其振幅被有效控制,输出电压随风速增加而减小;存在匹配电阻为250 kΩ时俘能器所产生的最大输出功率为3.78 mW。因此,该风致振压电俘能器在满足结构可靠、起振风速低及风速范围宽条件下同时可输出较大的电能。

A novel wind-induced-vibration piezoelectric-energy harvester with a deformable airfoil-shaped bluff body is proposed in this study to solve the problems of narrow wind speed bandwidths and excessive amplitudes at high wind speeds.The harvester mainly consists of a deformable bluff body,cantilever beam,and piezoelectric vibrator.The elastic wing of the bluff body deforms at different wind speeds,thus achieving the self-adjustment of the vibration characteristics and improving the environmental adaptability of the harvester.A COMSOL finite element model of the energy harvester is established,and the effect of wind speed on the shape and vibration characteristics of the bluff body is analyzed via simulations and ex⁃periments.In addition,the effects of windward angleθand elastic wing thickness e on the output perfor⁃mance of the energy harvester are determined.The results show that the wind speed bandwidth of the har vester ranges from 4 m/s to 25 m/s at a windward angleθof 120°and an elastic wing thickness e of 0.15 mm.Furthermore,the deformation of the elastic wing becomes small when the wind speed is lower than 8 m/s.When the wind speed ranges from 8 m/s to 17 m/s,the harvester experiences a transformation from galloping to vortex-induced vibration,resulting in a decrease in the output voltage.When the wind speed ranges between 17 m/s and 25 m/s,the bluff body has an arc shape because of the excessive defor⁃mation of the elastic wing.The harvester is dominated by vortex-induced vibration,and thus,its ampli⁃tude can be effectively suppressed.The output voltage decreases with increasing wind speed.Additional⁃ly,the test results show that the harvester can yield a maximum output power of 3.78 mW at a matching impedance of 250 kΩ.Both the theoretical analysis and experimental results indicate that the proposed har⁃vester can satisfy the requirements of high reliability,low cut-in wind speed,and broad wind speed band⁃width,as well as generate considerable electric power.