小型水平軸風力機的數值化開發測試平臺

本文完成建構一個250W六葉式水平軸風力機的數值模型，並使用計算流體力學軟體CFdesign作模擬分析，研究風力機的空氣動力特性。為正確計算風力機轉動與流體的作用力，模擬空間是三維的，不過為避免網格數量過多造成過大的計算量與誤差累積，本文採取多區域非結構網格劃分，僅在旋轉區域將網格加密以確保模擬結果的正確性。透過比較不同轉動角度與不同的網格劃分下的靜態轉矩得知，模擬系統所需的最佳化網格劃分不僅是網格密度要夠高，網格大小也要較均勻，才能正確描述流體網格與風力機網格的交互作用。而風力機的動態運轉模擬結果也顯示，網格的方式劃分嚴重影響風力機的角加速度與最終轉速。經最佳化的模擬系統，其計算出的靜態平均轉矩與最終轉速都與清雲科技大學風洞實驗結果相當吻合，驗證模擬系統的計算結果與實體實驗結果相符，因此該模擬系統將可作為小型水平軸風力機的開發測試平台。

關鍵字

計算流體力學(CFD) ；水平軸風力機(HAWT) ；空氣動力學

並列摘要

A numerical simulation model has been developed to be a testing platform for small size horizontal axis wind turbines (HAWTs). The simulation model is created for promoting the blade design and the full set performance of a 250W HAWT with six blades. One computational fluid dynamics (CFD) software is applied to build up the system. A three-dimensional simulation space is used to describe interactions between the fluid and the rotating device. In order to decrease the total number of grids and computation loading, multi-region and non-structural meshing method is applied in this model. Distributions of the blade static torques for different rotating angles under different mesh sizes are examined to find the optimal grid meshing. It helps us to ensure the results are trustable. Dynamic simulations for free rotation are performed under the input wind speed of 10m/s. The rotating speeds and torques on the blades in numerical results agree well with the experimental measurements performed in the wind tunnel of Ching Yun University. It indicates this numerical model can be a powerful platform to examine new design or modification of the blades.