本研究使用計算流體力學軟體FLUENT模擬小型風車流場，分析其空氣動力特性，並將模擬結果與風洞中實際之小型風車實驗測試所得之實驗值進行比對，主要目的為驗證數值模擬結果應用於實際風車之效能分析可行性。 本文採用NACA2415與NACA4415作為小型風車之葉片翼型。先利用電腦輔助設計軟體Pro-Engineer描繪出模型後，以線面體方式在網格產生器Gambit裡逐步長成非結構網格，再以數值計算結果，並探討雙葉片與三葉片小型風車之數值與實驗比較。 研究結果發現，網格密度對數值計算結果影響極大，以二維翼剖面為例，若要得到精確解則必須有一定密度之網格。而雙葉片小型風車之數值計算結果雖然與實驗值有誤差，但趨勢上皆相似，三葉片小型風車之實驗值與數值計算結果相當吻合，因此證實了數值計算能夠應用於實際風車流場之計算。 In this study, computational fluid dynamics software FLUENT was used to simulate the flow field of small wind turbines. To explore the feasibility of using FLUENT to design small wind turbines, a series of tests were also conducted in a small wind tunnel. Two airfoil shapes, NACA2415 and NACA4415, were used as the blade shapes of the small wind turbines. We first used the computer aided design software, Pro Engineer, to draw the configuration of the wind turbines. A line, surface, and body approach was used in the grid generator, GAMBIT, to generate unstructured grids for the wind turbines. FLUENT was then used to simulate two- and three-blade wind turbines. The calculated power coefficients were compared with the experimental data to validate the numerical results. The research showed that grid density has decisive effects on the accuracy of the numerical solutions. We used a two-dimensional wing profile as an example and demonstrated that a very high grid density is needed near the airfoil surface if accurate results are to be obtained. The errors between calculated and experimental power coefficients were larger for two-blade wind turbines. But the trend of the curves is similar. The corresponding errors are much smaller for three-blade wind turbines. Finally, we feel that numerical simulation can be an efficient tool in designing small wind turbines but more validations are needed before it becomes a reality.
