臺灣博碩士論文加值系統

浮體式風機所搭配之浮體平台對其受風與波浪耦合作用下之運動程度扮演重要的角色，在離岸風場位址選擇受陸上地形及風切影響較小之浮體平台有利於減少風機之發電量損失。本研究以NREL 5MW風機當作目標風機，並分別搭配OC3-Hywind之Spar型浮體平台與OC4 DeepCwind之半潛型浮體平台為計算模擬之對象。研究方法為雷諾平均納維爾史托克(RANS)求解浮體平台受水動力作用之流場並選用適當的紊流模型及額外搭配BEM程式估算風機之氣動力性能。以BEM進行目標風機之氣動力性能計算結果與NREL公佈之資料相互驗證，轉子功率計算結果與資料趨勢相符，額定風速(11.4m/s)下之差異約為7.64%。BEM程式於縱搖運動下修正之計算結果顯示考慮真實風機之控制情形其平均功率會下降，且風機推力與功率變動週期與縱搖角速度週期相同，與參考文獻以RANS計算之結論相符。耦合BEM與CFD軟體計算浮體式風機於波高4m週期10s之規則波中進行縱搖運動之數值模擬，並比較Spar型與半潛型浮體式風機之實際發電平均功率耗損率以半潛型浮體式風機之耗損率較小，此結果與文獻亦相同，顯示耦合BEM與CFD軟體計算浮體式風機受風、波耦合作用下之可行性。藉由不同的波浪參數探討以發電量為目標時Spar型浮體式風機與半潛型浮體式風機之適用範圍，由數值模擬結果顯示當波浪週期小於8.4s之線性波，將選則Spar型浮體式風機；當波浪週期大於10s與波浪近似於靜水狀態則選擇半潛型浮體式風機能夠減少功率損失。

The offshore wind turbine will be influenced by the couple of aerodynamics and hydrodynamics.The selection of floating platform will directly affect the generating power of the wind turbine. The floating system of the OC3-Hywind and the OC4 DeepCwind is applied in this paper. Through the Blade Element Momentum theory evaluate the power curve of NREL-5MW wind turbine and compare to the NREL data. It shows two of them have similar power curve, but they have about 7.64% difference in the rating velocity condition. When we consider the real wind turbine control system in the pitch motion, the average power is no longer that high anymore. Within the motion of turbine, it causes the power of turbine have the same period as the motion of turbine.
In this paper, coupling the Blade Element Momentum (BEM) and computational Fluid Dynamics model (CFD) to evaluate two type of floating wind turbine, spar and semisubmersible wind turbine. Under the wave height 4m and period 10s, it shows that the semisubmersible type floating wind turbine has lower power loss than the spar type of wind turbine. This simulation case is verified with the reference.
According to this research present a suitable wave condition to reduce the power loss for both of the floating wind turbine. If the wave period is less than 8.4s, so the spar type floating wind turbine has been recommended. But if the wave period is larger than 10 s and the wave is just like calm sea state, the semisubmersible floating wind turbine will be better.

摘要 Ⅰ
ABSTRACT Ⅱ
目錄 Ⅲ
圖目錄 Ⅵ
表目錄 Ⅹ
符號表 XII
第1章緒論 1
1.1研究背景 1
1.2離岸型風力發電介紹與浮體式風機介紹 3
1.3文獻回顧 8
1.4研究目的與方法 9
1.5本文架構 11
第2章理論基礎 12
2.1計算流體力學 12
2.1.1統御方程式 12
2.1.2紊流模型 13
2.1.3壁面函數 15
2.1.4數值方法 18
2.1.5雙相流數值方法 19
2.2風力發電機理論 20
2.2.1動量理論 20
2.2.2葉片元素理論(Blade Element Theory) 25
2.2.3葉片元素動量理論(Blade Element Momentum Theory) 28
2.3剛體運動 32
2.3.1浮體式風機六自由度運動 32
2.3.2線性波浪力學 35
2.3.3錨鍊系統 35
2.3.4風機於強制縱搖運動之推導 39
第3章浮體式風機幾何與數值驗證 43
3.1目標風機資料與幾何參數 43
3.2 BEM程式流程 51
3.3浮體平台幾何與錨鍊系統 56
3.3.1 Spar型浮體平台 32
3.3.2半潛型浮體平台 59
3.4數值模擬驗證 62
3.4.1圓形數值模擬與驗證 62
3.4.2純波浪數值驗證 67
第4章浮體式風機數值計算 72
4.1強制縱搖運動下風機性能計算 72
4.2繫錨力初始值計算 75
4.2.1 Spar型浮體風機繫錨力初始值計算 75
4.2.2半潛型浮體風機繫錨力初始值計算 79
4.3 Mooring、BEM與RANS耦合計算浮體風機受規則波作用之性能 82
4.3.1流場範圍與邊界條件 83
4.3.2網格佈置策略 85
4.3.3邊界條件驗證 86
4.3.4 Spar型浮體風機於波高4m週期10s之計算 87
4.3.5 Spar型浮體式風機於波高5.2m週期10s之計算 89
4.3.6 Spar型浮體式風機於波高3.6m週期8.4s之計算 90
4.3.7半潛型浮體風機於波高4m週期10s之計算 91
4.3.8半潛型浮體風機於波高5.2m週期10s之計算 93
4.3.9半潛型浮體風機於波高3.6m週期8.4s之計算 94
4.4浮體式風機於縱搖運動下數值驗證 95
4.5浮體式風機於縱搖運動下之比較 97
4.5.1 Spar型與半潛型浮體平台差異 97
4.5.2波高對浮體式風機之影響 100
4.5.3固定波浪陡峭度波高對浮體式風機之影響 100
4.5.4浮體式風機之適用範圍 103
第5章結論 105
REFERENCE 107

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