臺灣博碩士論文加值系統

本文主要針對浮筏式蚵架遭受環境外力時之動力特性進行研究。浮筏式蚵架牡蠣養殖為台南淺海貝類養殖之重要經濟來源，主要浮筏式蚵架養殖具有下列特質：(1)成本低，(2)施工便利，及(3)搬運方便等優點，為我國牡蠣主要養殖方式。由於浮筏式蚵架之結構無法抵抗颱風之侵襲，故在颱風季節來臨前，即被拖往港內避開風浪之破壞。但由於一些無法預測之惡劣海象仍可能發生，並造成浮筏式蚵架之嚴重損壞；因此有必要就海上浮筏式蚵架之動力特性進行研究。本研究採用自行發展之數值模式及水工模型實驗等方法，探討浮筏式蚵架遭受波流交互作用下，錨碇纜繩所承受之張力與蚵架之運動行為。數值方法是以質量集結點法為基礎，配合修正後之Morison equation計算各構成桿件之環境外力，組成運動聯立方程式，再經由4階的Runge-Kutta法求解浮筏式蚵架之運動方程式，即可獲得浮筏式蚵架之動力特性。為驗證數值模式之準確性，製作浮筏式蚵架水工模型進行一系列之實驗，其結果顯示數值模式之預測值與水工模型實驗值具有相當之吻合性。
海上現地養殖，則以台南鄰近海域之貝類養殖場為案例，探討實際蚵架錨碇纜繩承受張力、最佳間距、與最佳錨碇纜繩長度，以提高牡蠣養殖系統之安全性，供牡蠣養殖業者參考。研究結果建議整組蚵棚產生最低張力之最佳規劃如下: 蚵架間距為一倍的單一蚵架長度；錨碇纜繩越長其所承受張力越小，建議採用3倍水深即可，與目前牡蠣養殖區採用3～4倍水深之錨碇纜繩一致；錨碇塊則採用澎湖養殖業者所有之鐵錨型式70 kg。最後本研究冀望能提供浮筏式蚵架系統之設計方針，以減少因海象突然變化造成之損失。

The purpose of this study is to investigate the hydrodynamic properties of an oyster floating raft system under environmental loadings. The floating raft system is an important facility for raising oyster in the near shore area of Tainan, Taiwan. The reasons for this kind of oyster culture being main income source for local fish farmers are as the following features: (1) low cost for the farming system, (2) easily to be installed in the field, and (3) easily to be harvested. Due to the raft structure could not withstand the impact of heavy storms; most of the oyster rafts are towed into harbor to avoid damage before the onset of typhoon. Since some unexpected violent sea states may occur and severely affect the integrity of raft system, the investigation of the hydrodynamic properties of a floating raft system is essential for oyster culture in the open sea. This study includes two parts: numerical simulation and physical modeling. In numerical simulation, a lumped mass method with a Morison type of relative motion equation are adopted to calculate the drag and inertial forces on raft components and then are equally divided to the associated nodes to form a system of motion equations based on Newton’s second law. Through the fourth-order Runge-Kutta method, the dynamic performance of the oyster raft system can be obtained. To verify the numerical model, a physical model was carried out in a wave tank (35x1x1.2 m), and the results of dynamic performance of numerical model show good agreement with measurements.
A case study of an in situ oyster farming system located near-shore of Tainan region is analyzed by the developed numerical model to investigate the maximum mooring tension, the optimal gap between rafts, and the required length of mooring line. These specifications are crucial to the shell fish farmers for their floating raft system to be survived in the strong currents and waves. The results showed that the optimum configuration for a raft system generated the lowest mooring tension is as the follows: the space between oyster rafts is about a length of oyster raft; the length of mooring line is three times of the water depth, which is consistent with the present practice of shell fish farmers adopting 3~4 times of water depth; the appropriate embedment anchor weight is 70 kg but the anchorage should be the type used by the farmers in Penghu county. Finally, this work intends to offer a guideline for the installation of oyster raft systems in the field, and anticipate minimizing the damage during the unexpected heavy sea states.

摘要 i
Abstract iii
表目錄 ix
圖目錄 xi
符號對照表 xv
第一章 緒論 1
1.1 前言 1
1.2 文獻回顧 2
1.3 研究目的 3
1.4 本文組織 3
第二章 浮筏式蚵架基本理論 5
2.1 浮筏式蚵架結構簡介 7
2.1.1 錨碇系統 9
2.1.2 保麗龍塊 10
2.1.3 蚵架系統 10
2.1.4 牡蠣串 11
2.2 波流場之基本假設 11
2.3 浮筏式蚵架結構受力分析 15
2.3.1 流阻力及慣性力 15
2.3.2 重力 16
2.3.3 浮力 17
2.3.4 張力 17
第三章 數值模式 19
3.1 質量集結點法概述 19
3.2 構件受力情況 20
3.2.1 纜繩 20
3.2.2 浮筏式蚵架 24
3.2.3 外加項(牡蠣叢) 28
3.3 質量集結點之運動方程式 32
3.4 Runge-Kutta法概述 33
3.5 計算機程式流程圖 34
第四章 水工模型實驗 37
4.1 實驗目的 37
4.2 模型縮尺 37
4.3 水工模型製作 38
4.3.1 蚵架模型 38
4.3.2 仿牡蠣模型 39
4.3.3 錨碇板 40
4.3.4 纜繩 40
4.4 實驗儀器設備 40
4.5 實驗佈置 48
4.6 實驗步驟 48
4.7 實驗設定條件 51
4.8 實驗分析方法 51
4.8.1 張力分析 51
4.8.2 蚵架剛體運動分析 51
第五章 數值模式與水工實驗結果分析 55
5.1 牡蠣拖曳力係數之檢定 55
5.2 蚵架受力分析 58
5.2.1 純流實驗結果 58
5.2.2 純波實驗結果 59
5.3 蚵架運動及張力分析 61
5.4 數值模式應用 64
5.4.1 設定條件 64
5.4.2 最佳蚵架間距分析 65
5.4.3 最佳錨碇纜繩長度分析 67
5.4.4 蚵棚案例分析 71
第六章 結論與建議 77
參考文獻 81
附錄A 纜繩材料尺寸資料表 83
附錄B 質量慣性矩 84
附錄C 纜繩破斷強度試驗 86
附錄D 影像處理 87
附錄E 剛體運動 95

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