臺灣博碩士論文加值系統

本文對完整的NREL 5MW型離岸風機在額定風速(11.4 m/s)和固定轉速(12.1 rpm)的條件下，使用基於旋轉座標的流固耦合數值方法，估算風機葉片變形，進行考慮葉片變形之旋轉風機的暫態氣動力特性與噪音分析。風機周圍不可壓縮流場計算，是基於求解納維爾史托克斯方程組及k-紊流模型，利用有限體積法進行控制方程式離散，暫態計算過程中採用滑動網格方式模擬風機葉片的旋轉運動，並藉由FWH模型(Ffowcs Williams Hawkings model)將風機周圍流場之速度與壓力變化轉換為聲壓變化，以計算風機葉片之噪音特性。本研究在流固耦合計算中，使用Abaqus軟體計算具複合材料特性葉片之變形，並使用STAR-CCM+ 軟體以旋轉網格方式模擬葉片之轉動模式，本研究利用Abaqus 與 STAR-CCM+ 之往復計算以獲得彈性葉片的穩定變形量。由旋轉葉片暫態模擬結果比較得知，彈性葉片的輸出功率較剛性葉片的輸出功率下降約2.35%，而由噪音頻譜分析可以得到，當偵測點位於風機後方15m處，彈性與剛性葉片產生的總噪音值變化不大，而當偵測點位於風機後方125m處時，彈性葉片所產生之總噪音值明顯地大於剛性葉片約10%。

In this study, the full-scale numerical simulations are performed at rated wind velocity (11.4 m/s) and rated rotor speed (12.1 rpm). The aerodynamic and aeroacoustic prediction of a NREL 5MW offshore wind turbine is performed via a Fluid-Structure Interaction (FSI) approach. The Navier–Stokes equations are used to describe the incompressible and viscous flow around the wind turbine. A k- model is adopted to take the turbulence effects of wind into account. This study used a finite volume method to discretize the governing equations. The FWH model is employed to convert the velocity and pressure change of the flow field into the sound pressure level to determine the noise characteristics. In the simulation, Abaqus is used to calculate the structure deformation of blades, whereas STAR-CCM+ is employed to simulate the flow field. With the calculation switching between Abaqus and STAR-CCM+, the stable position of deformed blades can be obtained. The power decreases about 2.35% for flexible blades when compared with that of rigid blades. The change of total sound level is not obvious between flexible and rigid blades when the detecting point is 15m behind the wind turbine. The total sound level of the flexible blade is about 10% higher than that of the rigid blade when the detecting point is 125m behind the wind turbine.

摘要 2
Abstract 3
目錄 4
符號表 6
圖目錄 11
表目錄 14
第一章 緒論 15
1-1 文獻回顧 15
1-2 研究目的 17
1-3 目標風機 18
第二章 數學模型與數值方法 26
2-1 流場方程式 26
2-2 流場離散數值方法 32
2-3 結構方程式 33
2-4 流場計算之網格獨立性分析 36
第三章 葉片變形計算 38
3-1 基於旋轉座標系的流場計算 38
3-2 基於旋轉座標系的結構計算 42
3-3 流固耦合計算方法 44
3-4 流固耦合計算結果 46
第四章 旋轉風機流場計算 52
4-1 使用滑動網格的流場計算 52
4-2 計算例條件說明 53
4-3 風機氣動力計算 54
4-4 風機噪音計算 66
4-5 風機流場計算 72
第五章 結論與未來工作 81
5-1 論文總結 81
5-2 未來工作 82
參考文獻 83

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