本研究之目的在以CFD模擬進行JBC之導罩設計，並以自推模擬之結果驗證所設計之導罩與船體和螺槳之交互影響是否改善整體推力及阻力。CFD模擬使用OpenFOAM，考慮其為開源軟體；模擬條件設定與結果比對參考Tokyo 2015 Workshop on CFD in Ship Hydrodynamics網站中所提供之實驗資料，以確保模擬之準確性。
導罩設計分四個階段：首先透過驗證與確認(Verification & Validation)方法建立具獨立性和可靠性之模擬設定，第二步再透過此設定將不同角度的軸對稱導罩之阻力模擬以收斂的阻力平均值進行分析，第三步依據分析結果整合設計非軸對稱之導罩並以阻力模擬確認其減阻效果，最後將所得較佳之設計進行自推模擬並分析全船交互作用下之減阻及減推效果。
阻力模擬與自推模擬之阻力和螺槳推力皆通過驗證與確認，並且阻力模擬結果與船模實驗之結果相比最佳僅有1.78%之誤差；自推模擬之阻力結果與船模實驗之結果相比最佳僅有4.29%之誤差，同時螺槳推力僅有1.63%之誤差。
阻力模擬結果顯示，本研究建立的導罩設計對JBC船型具有良好的減阻效果，最佳之非軸對稱導罩可以達到2.59%之減阻效果。在自推模擬結果中，最佳之非軸對稱導罩之推進係數能高達0.8806，與原導罩相比有5.77%之提升。

The goal of this study is to design a duct which is an ESD (Energy Saving Device) installed in the stern of the ship to improve the energy-saving performance of JBC (Japan Bulk Carrier). The original design of the duct is an axisymmetrical foil section, with a resistance reduction of 0.6% comparing with the result of bare hull resistance.
As a result of high cost and time-consuming of EFD (Experimental Fluid Dynamics), this study will be using CFD (Computational Fluid Dynamics) to design a new duct for JBC. To ensure the integrity and consistency of the result of CFD, V&V (Verification & Validation) approach is used. We compare the simulation results with the EFD results provided by Tokyo 2015 Workshop on CFD in Ship Hydrodynamics(T2015) website to assure the reliability and low uncertainty of the settings. After the appropriate conditions of the simulations are set, the settings are then used to generate the results of different duct designs.
Through analyzing the results of the resistance simulation of JBC with symmetric ducts through OpenFOAM, the opensource CFD software, different sets of non-symmetric ducts are then designed and tested with CFD. Comparing the results of original duct and the best designed duct, the reduction in resistance can be up to 2.59%. Afterwards, self-propulsion simulations are conducted with most of the better designed duct from resistance simulation. The results of the designed ducts are then used to calculate the propulsion efficiency, which the best design can provide up to 5.77% improvement compared to the original duct for JBC.

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