向低碳經濟的轉型是目前的全球趨勢，然而取代傳統化石燃料發電的可再生能源具有供應安全性匱乏的擔憂，因為雖然越來越多的可再生能源是可以預報的，例如風能和海洋能，但其能源的產生卻是隨機且間歇性的。為了尋找清潔、可再生能源，海洋、河流與河口水流的動能皆是對環境無害的能源，因此相關研究也陸續展開。利用潮汐和河流水力能量的渦輪機通常被稱為作為水力渦輪機。目前的研究主要集中在設計水平軸外罩式水力渦輪加速設備和基於計算流體動力學（CFD）的流動加速設備性能評估。工作的基本目標是評估外罩式水輪機的性能與發電功率在有無加裝流體加速裝置的情況下的差異情形。
本研究針對不同幾何形狀的流體加速器對水輪機性能提升的差異。首先，對沒有加裝流體加速裝置的外罩式水輪機進行數值模擬驗證。其次，分析比較不同面積比與不同形式的流體加速裝置的性能差異以及3D流線、壓力場、速度場和質量流率。
結果證實有加裝流體加速器的外罩式水輪機其性能有顯著的改善，有流體加速器的外罩式數水輪機其最大功率係數為1.34，而無流體加速器的外罩式水輪機為0.89。因此，在外罩式水輪機加裝流體加速器可以增加最大達50％的性能表現，提升單一機組下的發電功率與能源利用效率。

Transition towards a low carbon economy raises concerns of loss of security of supply with high penetrations of renewable generation displacing traditional fossil fuel based generation. While wind and wave resources as renewable energy are increasingly forecastable, they are stochastic in nature. In the search for clean, renewable energy, the kinetic energy of water currents in oceans, rivers, and estuaries is being studied as a predictable and environmentally benign source. Turbines developed for the power production from the energy of tidal and river currents are commonly referred to as hydro current turbines. The current research focused on designing the flow acceleration devices for a horizontal axis ducted hydro current turbine and to evaluate the performance of the flow acceleration devices based on computational fluid dynamics (CFD). The underlying goal of the work was to assess the potential augmentation of power production associated with enclosing the ducted turbine in a flow acceleration device. Thus, a comparison of the potential performance of ducted turbine with and without flow accelerators was carried out.
The effect of various flow accelerator geometries on the performance of ducted water turbine was studied. Firstly, the coefficient of performance of the flow accelerator of same area of inlet and outlet and flow accelerator of various ratio of outlet area to inlet area were compared to ducted water turbine without flow accelerator. Secondly, the flow field around the ducted turbine with flow accelerator was analyzed in terms of developed 3D stream line, the pressure field, velocity field and mass flow rate.
The results confirmed that the performance of ducted water turbine with flow accelerator gives a significant improvement than ducted turbine without flow accelerator. The maximum power coefficient for the ducted turbine was found to be equal to 1.34 for the turbine with flow accelerator and to 0.89 for the turbine without flow accelerator. Therefore, the maximum power coefficient was increased by 50% when the flow accelerator was used in the configuration.

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