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研究生:呂貫閩
研究生(外文):Guan-Min Lu
論文名稱:浮式結構物吸收波能之研究
論文名稱(外文):The Absorption of Wave Energy by Floating Structures
指導教授:吳永照
指導教授(外文):Yung-Chao Wu
學位類別:碩士
校院名稱:國立交通大學
系所名稱:土木工程系
學門:工程學門
學類:土木工程學類
論文種類:學術論文
論文出版年:2001
畢業學年度:89
語文別:中文
論文頁數:60
中文關鍵詞:浮式結構物波能效率
外文關鍵詞:floating structureswave energyefficiency
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依據二維線性波的理論,應用邊界元素法分析探討浮式結構物於有限水深處吸收入射波波能的效率。本文以每一週期所具有的功率來代表入射波波能,浮式結構物每一週期所吸收的波能與入射波波能的比值定義為效率,當結構物所吸收的波能與入射波波能相同,此時效率定義為最佳效率。本文模擬的結構物共三種:包括直角楔形、對稱楔形及直立平板;其中前兩者的運動方式為垂直振動,而最後者的運動方式則為水平擺動。
首先將數值結果與實驗值比較後發現兩者趨勢一致,證明本文數值模式的妥適性。研究中發現,若結構物後方為開放式的邊界,則結構物難以達到完全吸收波能的情況;當結構物後方為不透水牆時,由於增加反射波的作用,結構物在某些相對水深可以達到最佳效率;透過改變結構物的形狀及結構物與不透水牆的距離,最佳效率所對應的相對水深會隨之改變。換言之,藉由改變結構物的形狀及位置將可得到已知波浪條件的最佳效率。由本研究得知,直立平板其最佳效率所對應的相對水深範圍較廣,其次為對稱楔形,最差者為直角楔形;若考慮效率在0.9以上時,直立平板所對應的相對水深範圍最廣,直角楔形次之,最差者為對稱楔形;因此以本文探討的三種吸能結構物而言,使用直立平板水平振動方式來吸收波能為較佳選擇。
Based on a two dimensional linear water wave theory, the boundary element method is developed and applied to study the effectiveness of a wave energy absorber in water to finite depth. The present study is concerned with wave energy which is defined as the incident wave power per unit crest length, efficiency of an absorber defined as the ratio of the wave energy absorbed by the floating structures per wave period to the available energy of the incident wave, and the best efficiency defined as wave energy absorbed by structures and the available energy of the incident wave are the same. In this thesis, the structures have three forms: a right wedge, a symmetric wedge, and a vertical flat plat; we assume that front two structures are constrained to oscillate in heave, and the third structures is constrained to oscillate in sway.
The accuracy of the present numerical model is proved by comparing results of present numerical model, and laboratory experiment. When the boundary in back of the structures is radiation condition, the absorption of wave energy complete hardly by absorber, but exchange radiation boundary for vertical sidewall, the best efficiency was made in some relative depths. By changing the shape of the structures or the distance from structures to sidewall, the best efficiency relative to relative depths are different; in other words, the best efficiency of known wave conditions was got by changing the shape or location of the structures. Using the vertical flat plat to absorb wave energy, the arrange of the best efficiency relative to relative depths is wider than other two; considering above 90 percent of efficiency, using the vertical flat plat to absorb wave energy, the arrange of relative depths is also wider than other two. In summary, about three absorbers of the present study, the available of energy absorbed by vertical flat plat is better than others.
中文摘要I
英文摘要II
誌謝IV
目錄V
圖目錄VII
表目錄IX
符號表V
第一章緒論1
1-1 前言1
1-2 參考文獻2
1-3研究目的4
1-4研究方法4
第二章基本理論5
2-1 基本假設5
2-2 控制方程式6
2-3 數學模式的建立6
2-3.1 幅射問題數學模式8
2-3.2 散射問題數學模式10
2-4 浮堤受力分析12
2-4.1 幅射問題受力分析12
2-5.2 散射問題受力分析14
2-5 運動方程式15
第三章數值方法19
3-1 前言19
3-2 邊界元素法的概述19
3-3 邊界元素法的應用20
第四章結果與討論25
4-1 開放邊界垂直振動的效率驗証25
4-2 直角楔形垂直振動之模擬26
4-3 對稱楔形垂直振動之模擬28
4-4 直立平板水平振動之模擬29
4-5三種浮堤振動模擬之綜合比較30
第五章結論32
參考文獻35
圖目錄
圖2-1 可動浮式結構物配置圖39
圖4-1 數值模擬效率與實驗值比較圖40
圖4-2 數值模擬振幅比與實驗值比較圖41
圖4-3 直角楔形垂直振動效率、功率及振幅比與相對水深關係圖42
圖4-4 直角楔形垂直振動附加質量、阻尼係數及衝激力與相對水深
關係圖43
圖4-5 直角楔形垂直振動效率、功率及振幅比與相對堤距關係圖44
圖4-6 直角楔形垂直振動附加質量、阻尼係數及衝激力與相對堤距
關係圖45
圖4-7 直角楔形垂直振動不同相對堤距下效率與相對水深關係圖46
圖4-8 直角楔形垂直振動不同堤深下效率與相對水深關係圖47
圖4-9 直角楔形垂直振動不同堤角下效率與相對水深關係圖48
圖4-10直角楔形不同堤形在同一相對水深發生最佳效率比較圖49
圖4-11對稱楔形垂直振動效率與相對水深關係圖50
圖4-12對稱楔形垂直振動效率與相對堤距關係圖50
圖4-13對稱楔形垂直振動不同相對堤距下效率與相對水深關係圖51
圖4-14對稱楔形垂直振動不同堤深下效率與相對水深關係圖52
圖4-15對稱楔形垂直振動不同堤角下效率與相對水深關係圖53
圖4-16對稱楔形不同堤形及堤距效率分佈比較圖54
圖4-17直立平板水平振動效率與相對水深關係圖55
圖4-18直立平板水平振動效率與相對堤距關係圖55
圖4-19直立平板水平振動不同相對堤距下效率與相對水深關係圖56
圖4-20直立平板水平振動不同堤深下效率與相對水深關係圖57
圖4-21直立平板水平振動不同堤角下效率與相對水深關係圖58
圖4-22直立平板不同堤形及無因次堤距效率分佈比較圖59
表目錄
表4-1最佳效率發生在h/L=0.5附近效率比較表60
表4-2最佳效率發生在h/L=0.7附近效率比較表60
表4-3模擬浮式結構物於新竹海域吸收波能效率表(h/L=0.207)60
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