臺灣博碩士論文加值系統

為開發黑潮發電以擷取可觀之海洋再生能源，如何將水下浮游式海流渦輪機組錨繫於深水海底而能穩定浮游並發電，將成為這項技術最大的挑戰之一。為能控制浮游式海流渦輪機於設定水深，並於必要時能浮出水面或深潛，其系統外觀將一如一般水下載具，包含可提供靜浮力的胴體(機體)，可提供動升力的翼及控制面，擷取和轉換能量的旋轉葉片及包含發電機在內的機艙等元件組成；此外藉由纜與錨所構成的錨繫系統將之固定於海底。本研究在於探討浮游式海流渦輪機在穩定海流流速下之繫纜張力。海流渦輪機之流體動力是應用CFD軟體 ANSYS-FLUENT進行計算，而繫纜之數學模式引用有限元素模式(Finite Element Model)予以建構。海流渦輪機及繫纜所構成之力學系統之平衡方程式求解，則應用程式軟體MATLAB撰寫。本研究以海流流速1.5 m/s時，額定輸出0.5 MW為一機組之系統為例進行探討，且一機組是由左右配置而對轉的葉片所組成，本研究探討在穩定海流作用下，該浮游式海流渦輪機組的受力及繫纜的形狀和張力。

In order to harvest Kuroshio Current energy, anchoring and mooring technology of floating marine current turbines is one of the key challenges. A floating marine current turbine needs to float stably at a proper depth for generating power steady, and also needs to go up to the surface for maintenance, or even to go down deeper to avoid the influence of waves caused by Typhon. Therefore, in addition to rotor and nacelle for harvesting energy, it may look similar to an underwater vehicle with a fuselage for offering static buoyancy, wing and control surfaces for offering dynamic lift. Besides, it is connected by a wire or rope to the anchor, which is fixed at the seabed.
In the present study, the tension forces of the mooring line for a marine current turbine floating in a steady current of constant speed is investigated. CFD software ANSYS-FLUENT is adopted to calculate the hydrodynamic forces of the turbine, and Finite Element Model is applied to simulate the mooring line. The force equilibrium equations of the whole system including the turbine and mooring line are solved by a program of MATLAB. The rated power of the simulated turbine with counter rotating twin rotors at current speed of 1.5 m/s is about 0.5 MW. Steel wire and polyester rope are investigated as the mooring line in the present study.

第一章 緒論.....................................1
1-1 前言.....................................1
1-2 研究方法及本文架構.......................5
第二章 數學模式.................................6
2-1 水下繫纜之數學模式.......................6
2-1-1 基本假設.................................7
2-1-2 繫纜座標系統.............................7
2-1-3 繫纜受力狀況.............................9
2-1-4 水流阻力R_u,R_v 及R_w之定義.............10
2-1-5 繫纜座標系統及空間座標系統之轉換........13
2-2 渦輪機阻力模式..........................14
2-2-1 動量理論................................14
第三章 數學模式................................17
3-1 網格生成與品質..........................17
3-1-1 網格產生方式............................17
3-1-2 數值擴散................................17
3-1-3 網格品質................................18
3-2 統御方程式..............................18
3-3 紊流模型................................21
3-3-1 Realizable k-ε紊流模型..................21
3-3-2 紊流強度................................22
3-4 浮式海流渦輪機之數值方法................23
3-4-1 有限體積法..............................23
3-4-2 流場壓力速度耦合求解....................23
3-5 水下繫纜之數值方法......................24
3-5-1 四階Runge-Kutta method..................24
第四章 數值驗證及計算..........................26
4-1 渦輪機之流體力計算......................26
4-1-1 模型....................................26
4-1-2 渦輪機半徑..............................27
4-1-3 渦輪機模擬驗證..........................27
4-1-4 邊界條件設置............................29
4-1-5 網格獨立性..............................30
4-1-6 計算域驗證..............................31
4-1-7 雷諾數驗證..............................31
4-1-8 挖孔圓盤之阻力係數......................32
4-2 水下浮游式海流渦輪機之流體力計算........33
4-2-1 水下載具外型及尺寸......................33
4-2-2 水下浮游式海流渦輪機之座標系............35
4-2-3 水下浮游式海流渦輪機網格數驗證..........36
4-2-4 繫纜與海流渦輪機相繫點與力矩之關係......38
4-2-5 水下浮游式海流渦輪機之六方向受力........39
4-3 繫纜靜力分析結果........................39
4-3-1 繫纜之數值計算流程......................39
4-3-2 繫纜數值驗證............................39
4-3-3 鋼纜....................................42
4-3-4 聚酯纖維纜..............................45
4-3-5 渦輪機位置及繫纜張力於不同流速下之關係..47
4-3-6 渦輪機升至海平面時繫纜之特性............49
第五章 結論與展望..............................53
附錄一：無因次參數
附錄二：流體動力係數
附錄三：軸向誘導因子a與功率係數C_p 及阻力系數C_d之關係如下表
附錄四：海水密度
附錄五：美國The gulfstream海流發電機四視圖
附錄六：水下載具模擬計算與實驗比較驗證資料
附錄七：圖4-8水下浮游式海流渦輪機放大圖與網格設置圖

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