本研究利用CFD方法針對水渦輪機三維流場進行數值模擬研究，數值方法採用CFX有限體積法求解三維Reynolds-Averaged Navier-Stokes方程式，配合k-ε紊流模型與非結構性網格，探討一個小型水渦輪機在有無安裝外罩的情況下其效率的差別，並探討不同葉片安裝角度變化下的性能特性，以期在廣泛的流速條件下均能夠有優異性能的發揮。探討的模型是以一具1KW額定輸出功率的小型水渦輪機為基礎，流速範圍為1m/s至10m/s，安裝角變化角度由基礎的角度為基準調整範圍由-15度至30度，轉速固定為240rpm。研究的重點在於不同葉尖速比的條件下整體扭力及功率的輸出，與其效率的表現，並據以訂立在各種操作環境下的控制邏輯，以達水渦輪機最佳性能發揮的基礎。論文中討論數值仿真方法、物理模型、重要參數條件、結果的探討及建議達最佳性能發揮的控制邏輯，以做為未來設計者的參考。

This research simulates the 3-D flow-field and the performance of a shrouded small water turbine at various pitch angles by using CFD method. The comparisonsof the power and torque for the turbine with and without shroud are also discussed. The solving CFX numerical method numerically with finite volume method and involving the k-ε turbulence model and unstructured grid was adopted.The purpose of the study is expected to find out a good logic of pitch angle change for the water turbine at wide range of operating conditions. The baseline model adopted is a small water turbine with 1KW rated output. The stream speed range in study is in between 1m/s to 10m/s. The pitch variation is from -15 degrees to 30 degrees, based on the baseline design. The rotational speed is kept 240rpm at all operating conditions. The major focus is to discuss the torque, power and efficiency output at various blade tip speed ratios (TSR). The obtained data are used to determine the control logic for blade pitch angle selection for the water turbine to achieve the optimal performance. In this paper, the numerical method, physical model, selected parameters for study, main results, and finally the suggestion of control logic to achieve the best performance over a wide operating range are discussed for design reference.

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