臺灣博碩士論文加值系統

大自然中有許多渦漩能量，像是大氣中為人熟知的颱風、龍捲風，水中泳者擔心的漩渦。根據Kim (2013)反置魚板擺動實驗和文吉 (2016)半圓柱後方魚板擺動實驗，我們結合此二者想法以開發新渦漩擷取能量，故本實驗以鈍角三角柱產生卡門渦街流場，並在後方放置一非撓性自由轉動反置魚板，藉由改變流場流速、魚板長度和魚板與三角柱距離，觀察各種不同變因之現象，並藉由數值模擬來更加了解其現象原因。
前人研究一方面為不同柱體產生之卡門渦街現象觀察，量測不同柱體所得到的阻力係數(Drag coefficient)，一方面為藉由實驗以及數值模擬來研究反置魚板自己因為流場而引發的擺動。我們將反置魚板置於三角柱後方，藉由雷射、流場顯影粒子和相機拍攝流場，並用PIV lab觀察並計算各流場資訊，以推測各實驗結果之可能原因，作為之後擷取渦漩能量前置作業。
在不同的魚板長度和流速下，反置魚板會有各種不同的擺動現象，其中長度0.35D的反置魚板在某條件下有我們感興趣之反向雙邊擺動現象。從實驗的流場觀測亦能得知卡門渦街會隨著柱體後方物體改變，當魚板長度越長時所受到的改變越大。
不同的柱體會產生不同之卡門渦街，就此實驗所測試之四柱體，我猜測鳥翼型柱體會是擷取渦漩能量之一大利器。

There are lots of vortex energy in the nature, for example, the known tornadoes and the whirlpool scaring swimmer. I want to explore new method of vortex energy harvesting. According to Inverted-flag experiments and the experiment of flapping fish model behind semicircular cylinder, I produce the Karman vortex street by triangular prism and put an inflexible inverted flag which is free-rotating. Change free stream velocity, length of flags and the distance between inverted flag and triangular prism. Then observe and record the results and use numerical analysis to know the reason of the flapping results more.
Some of researches are the Karman vortex street of different shapes of column and their Drag coefficient. Some are flapping of the inverted flags. I put inverted flag behind triangular prism and use laser, Polyamide Seeding Particles and camera to get the pictures of flow field. Then figure out the reason of the results by numerical analysis.
At different length of flags and velocity, there are several flapping conditions of inverted flag. There is reverse double-side flapping when the length of inverted flag is three and a half times of characteristic length. By observing the flow field of experiment, we know that the flags behind column will affect the Karman vortex street and more seriously when the length of flags is longer.
Flow over different shapes of cylinder will occur different forms of Karman vortex street. I think the wing-form cylinder is the best instrument of harvesting vortex energy of four cylinders in this experiment.

誌謝 I
中文摘要 II
ABSTRACT III
目錄 V
圖目錄 X
第一章 緒論 1
1.1 前言 1
1.2 文獻回顧 1
1.2.1 流場尾流分析 1
1.2.2 Vortex-induced Vibration 3
1.2.3 反置魚板 3
第二章 實驗設備與實驗方法(步驟) 6
2.1 實驗設備 6
2.1.1 水平式水洞 6
2.1.2 PIV系統 7
2.1.2.1 雷射 7
2.1.2.2 電子耦合攝影機 8
2.1.2.3 流場可視化粒子 8
2.1.2.4 PIV分析程式 9
2.1.3 實驗模型 10
2.1.3.1 鈍角三角柱 10
2.1.3.2 銳角三角柱 11
2.1.3.3 半圓柱 12
2.1.3.4 鳥翼型柱體 12
2.1.3.5 支架及夾具 13
2.1.3.6 長度0.2D~0.5D之魚板 14
2.2 實驗步驟 15
2.2.1 雷射 15
2.2.2 架設與量測 15
2.2.3 攝影及PIV分析 16
2.2.4 結束後收拾 16
2.3 實驗方法 16
2.3.1 第一階段：卡門渦街 16
2.3.2 第二階段：卡門渦街與反置魚板交互作用 16
第三章 理論分析 18
3.1 無因次參數 18
3.1.1 雷諾數(Reynolds number) 18
3.1.2 史卓荷數(Strouhal number) 18
3.2 基礎理論 19
3.2.1力矩與力之關係 19
3.2.2 力矩與角加速度之關係 19
3.2.3 轉動慣量 19
第四章 實驗結果與討論 21
4.1 實驗參數 21
4.2 水洞流速校正 21
4.3 卡門渦街流場觀測 22
4.3.1 直徑8公分半圓柱 23
4.3.1.1 流速0.12m/s，Re=9600 23
4.3.1.2 流速0.18m/s，Re=14400 24
4.3.1.3 流速0.24m/s，Re=19200 25
4.3.1.4 流速0.3m/s，Re=24000 26
4.3.2 底部8公分之鈍角三角柱(30, 30, 120) 27
4.3.2.1 流速0.066m/s，Re=5280 27
4.3.2.2 流速0.12m/s，Re=9600 28
4.3.2.3 流速0.18m/s，Re=14400 29
4.3.2.4 流速0.24m/s，Re=19200 30
4.3.2.5 流速0.3m/s，Re=24000 31
4.3.3 底3公分,高8公分之銳角等腰三角柱 33
4.3.3.1 流速0.066m/s，Re=1980 33
4.3.3.2 流速0.12m/s，Re=3600 34
4.3.3.3 流速0.18m/s，Re=5400 35
4.3.3.4 流速0.24m/s，Re=7200 36
4.3.3.5 流速0.3m/s，Re=9000 37
4.3.4 鳥翼型柱體(特徵長度8公分) 40
4.3.4.1 流速0.12m/s，Re=9600 40
4.3.4.3 流速0.24m/s，Re=19200 41
4.3.5 各柱體之(Strouhal number.渦街振幅)比較 42
4.4 卡門渦街和反置魚板交互作用之流場影像分析 42
4.4.0 實驗結果區域縮寫解釋 43
4.4.1 長0.2D之魚板 45
4.4.2 長0.25D之魚板 46
4.4.3 長0.3D之魚板 46
4.4.4 長0.35D之魚板 47
4.4.5 長0.4D之魚板 47
4.4.6 長0.45D之魚板 48
4.5 各情形之擺角-時間圖 48
4.5.1 單邊擺動情形(S) 48
4.5.2 雙邊擺動情形(I) 51
4.5.3 轉過去一般魚板位置擺動(F) 53
4.5.4 在一般魚板位置單邊小擺動(C) 55
4.6 各情形之流場示意圖及影片 57
4.6.1 不擺動情形(X) 57
4.6.2 單邊擺動情形(S) 59
4.6.3 二邊擺動情形(I) 61
第五章 模擬 63
5.1 簡介 63
5.2 步驟 63
5.2.1 建模 63
5.2.2 網格 64
5.2.3 流場計算 65
5.2.4 結果呈現 65
5.3 模擬結果與討論 66
5.3.1鈍角三角柱Strouhal number之模擬與實驗比較 66
5.3.2 不擺動情形(X)模擬 66
5.3.2.1 速度場(velocity) 67
5.3.2.2 流線(Streamline) 69
5.3.2.3 渦度(vorticity) 71
5.3.2.4 模擬和實驗比較 73
5.3.3 反置雙邊擺動情形(I)模擬 74
5.3.2.1 速度場(velocity) 75
5.3.2.2 流線(streamline) 77
5.3.2.3 渦度場(vorticity) 79
5.3.3.4 模擬和實驗比較 81
第六章 結論與未來展望 82
6.1 結論 82
6.2 未來展望 83
參考資料(REFERENCE) 84

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