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標題: | 結合非線性磁力的雙方向渦流誘發振動能量採集器之設計及分析 Design and Analysis of a Bi-directional Vortex-induced Vibration Energy Harvester with Magnetic Interaction |
作者: | Zong-Siang Wang 王宗祥 |
指導教授: | 蘇偉儁(Wei-Jiun Su) |
關鍵字: | 壓電能量採集器,雙方向,渦流誘發振動,磁力, Piezoelectric energy harvester,Bi-directional,Vortex-induced Vibration,Magnetic interaction, |
出版年 : | 2019 |
學位: | 碩士 |
摘要: | 由於傳統壓電懸臂樑能量採集器的頻寬過窄、採集方向單一等問題,使得使用上產生許多限制,因此為了改善此問題,本論文提出了一雙方向的框形樑結構並結合圓柱體之設計,並以風力作為振動源,來實現兩個方向的採集,使圓柱體產生週期性的渦流來激發採集器振動,也因渦流本身特有的非線性效應,即為「鎖定( lock-in )」現象,可以有效的拓增頻寬並提升輸出電壓。除此之外,本研究還加入了非線性的相斥磁力,希望透過磁力的影響,使結構剛性能夠符合預期的產生非線性變化,使整個採集器的有效共振風速區以及輸出電壓能夠更進一步的提升。 本研究對於理論模型的建立是先以古典樑理論與壓電本構方程式作為基礎,再推導出線性系統下的運動與電路方程式並以基底激振實驗進行驗證。非線性模型中則是以磁荷理論推導出方形磁鐵的磁力模型,再透過瑞利振盪器建立升力模型,並將兩者導入框形樑的線性模型中以求出非線性頻率響應。其中為了分析渦流誘發振動結合磁力的影響性,因此本研究以不同輔樑長度、不同磁鐵間距和電路接法來比較各項參數變化的效果,並以理論模型重現實驗環境中的渦流誘發振動下的動態響應。 實驗結果顯示,框形樑採集器在兩個方向上皆具有一定程度的採集能力,且磁力的加入也確實能對其中一個方向提升有效共振風速區以及輸出電壓,同時不影響另一方向的採集效果。其中,以輔樑長度為40 mm且磁鐵間距17 mm時,水平模態的有效共振風速區提升約34.8 %,串聯與並聯的輸出電壓分別上升約33.2 %和20.9 %作為最佳表現。 The applications of conventional piezoelectric cantilever energy harvesters are restricted because of the narrow bandwidth and single-directional sensitivity. Therefore, in order to overcome these problems, this study proposes a bi-directional frame-shaped beam with a cylinder to capture wind energy in two directions, when wind flows over the cylinder, periodic vortex is generated to stimulate the harvester to vibrate. It can effectively expand the bandwidth and increase the output voltage because of the nonlinear effect, which is the “lock-in” phenomenon. In addition, this study introduces use repulsive magnetic force to change the structural stiffness and nonlinearity so that the effective lock-in wind speed range and output voltage can be further increased. In the study, the motion and circuit equations of the theoretical model is derived based on the Euler-Bernoulli beam theory and piezoelectric constitutive equation. Base excitation experiment is conducted to verify the theoretical model. Finally, the magnetic force between two cubic magnets are derived based on the charge model. The lift model is established through the Rayleigh oscillator model. The two models are combined with the original linear frame beam model as a complete nonlinear magnetic-fluidic-electromechanical model to obtain the nonlinear frequency responses. In order to analyze the influence of vortex-induced vibration combined with magnetic force, this study uses different auxiliary beam lengths, different magnetic spacing and circuit connections to compare the effects of various parameter changes, and reproduces the dynamic responses under the vortex-induced vibration in the experimental environment by the theoretical model. The experimental results show that the frame-shaped beam harvester can gain notable energy in both directions, and the magnetic force can also increase the effective lock-in wind range and output voltage in one direction, while not affecting the harvesting efficiency in the other direction. Among them, the best performance is happened on the auxiliary beam length is 40 mm and the distance between the magnets is 17 mm, the effective lock-in wind speed range of the horizontal mode is increased by about 34.8 %, the output voltage of the series and parallel connection is increased by about 33.2 % and 20.9 %, respectively. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/62138 |
DOI: | 10.6342/NTU202000775 |
全文授權: | 有償授權 |
顯示於系所單位: | 機械工程學系 |
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