本研究建立一套計算流體力學 (Computational Fluid Dynamics, CFD)模式以模擬NREL 5-MW baseline turbine在單轉子(Single Rotor)及全風機(Full Wind Turbine)情況下空氣動力表現(Aerodynamic Performance)，並利用統計方法分析於穩態模式(Steady State)下，不同額定風速(Rated Wind Speed)下之槳距角 (Pitch Angle)與有效功率及推力比間的關係，並歸納其他公開發表之數據以分別建立功率(Power)、推力(Thrust)與額定風速及槳距角之函數方程式(Functional Equation)。接著，利用暫態模式(Transient State)模擬轉子於通過塔架時的瞬時交互作用，最終導入大氣邊界層(Atmospheric Boundary Layer, ABL) 探討風機分別在東北、西南季風條件下，實際風場中的氣動力學表現。另外，根據參數化建模(Parametric Modeling)進行形狀優化的方式，風機葉片可經由超表面方法(Metasurface Approach)定義二維截面，並由非均勻有理B雲規曲線插值器(Non-Uniform Rational B-Splines (NURBS) Interpolator)完成風機葉片三維表面建模。在空氣動力模擬部分，本研究利用非結構化多面體網格(Polygon Mesh)離散化空間，藉此模擬高度彎曲和葉片的扭曲表面。經由網格獨立性測試(Grid Independence Test)所獲得之兼具經濟性及準確性的網格形式，後續將用以分析在不同風速及槳距角的風機尾流(Wake Flow)分佈、葉片表面的壓力係數(Pressure Coefficient)、剪應力係數(Shear Stress Coefficient)及極限流線(Limited Streamline)之分佈情形，以了解不同紊流模式(Turbulence Model)間的差異，及其造成在高額定風速下，有效功率及推力比降低的原因。此外，暫態模式還另外分析葉片通過塔架之間的瞬時空氣流動及扭矩、推力以及塔架阻力之時序列及能量振幅譜，還有流場風速剖面，以此獲得塔架效應(Tower Shadow Effect)以及大氣邊界層對風機空氣動力學性能的影響。

In this study, a computational fluid dynamics (CFD) model was developed to simulate the aerodynamic performance of the National Renewable Energy Laboratory (NREL) offshore 5-MW baseline wind turbine with single rotor and full wind turbine .Using statistical methods, the relation between pitch angle and performance when the speed is higher than the rated wind speed was analyzed; furthermore, other published data were compiled to establish the functional equations of power, thrust with various inflow wind speeds, and pitch angles. Then, the transient mode is used to simulate the instantaneous interaction of the blade when passing through the tower, and finally the atmospheric boundary layer is imported to discuss the aerodynamic performance of the wind turbine in the actual wind field under the northeast and southwest monsoon conditions, respectively. In addition, according to shape optimization based on parametric modeling, the two -dimensional cross -section of the wind turbine blade can be defined through a metasurface approach, and the three -dimensional surface modeling of the wind turbine blade, nacelle , and tower is completed using the nonuniform rational B -splines (NURBS) interpolator. In terms of aerodynamic simulation, the unstructured polygon mesh was used herein to discretize the space and simulate the highly curved and twisted surfaces of the blade. In terms of aerodynamic simulation, the polygon mesh was used herein to discretize the space and simulate the highly curved and twisted surfaces of the blade. In this study, the compact and accurate mesh form obtained through a grid independence test will be used to analyze the distribution of the pressure coefficient, shear stress coefficient, and limited streamline on the blade surface at various inflow wind speeds and pitch angles to understand the differences between different turbulence models and the causes of power and thrust attenuation at high inflow wind speeds. In addition, the transient mode additionally analyzes the time series of instantaneous air flow, torque, thrust, and tower drag as the blade passes through the tower; energy amplitude spectrum, and wind profile of the flow field to obtain tower effects and atmospheric boundary layers effects on wind turbine aerodynamic performance.

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