目前許多核子反應器安全分析nuclear reactor safety (NRS) 逐漸採用計算流體力學Computational Fluid Dynamics（CFD）的方法，其最大優點可獲得詳細的局部熱水流資料訊息，因此研究紊流模式對於燃料束組件的影響相當重要。本論文探討發展核電廠燃料組件數值模擬方法與提升CFD計算模組對於核能組件準確性之方法論驗證，進而分析燃料棒束內局部熱水流特性，而其特性對於格架設計以及燃料棒束的熱傳能力與完整性有很大的影響。這種三維局部的熱水流分佈特性，正是傳統安全分析工具無法模擬而CFD可以貢獻其能力之處。
研究針對模擬燃料棒組件，進行設計格架模組，以數值模擬的結果與實驗做比較驗證，進行分析討論燃料束流道熱水流現象，探討格點細化所對於模擬所造成的誤差，全尺寸與簡化尺寸的準確性，以及穩態與暫態的比較分析評估準確性。透過研究所獲得的模式基準來加以處理複雜的燃料組件結構，包括不同紊流模式 (Turbulence model)以及近壁面處理 (Near-wall treatment)方式等研究應用在燃料棒熱水流的誤差分析，其中利用近壁面Nusselt number得到燃料棒橫向與軸向分布的數值模擬比較基礎上。研究確認Realizable k-ε紊流模式對於燃料棒流道熱水流的計算結果提供精準的適用性，包括在使用CFD的計算時間上也較為經濟。在透過局部化的探討，包括流動、紊流和傳熱特性等現象，都能與實驗有相當接近的趨勢。研究將可提供更精確的格架葉片模擬校驗乃至於完整的反應器燃料束模擬與紊流模式靈敏度分析。因此，站在平行驗證或是協助核能管制單位審查分析的參考，對於燃料組件之混和葉片的格架設計其燃料棒束內的熱水流分佈特性之模擬分析，有相當重要的必要性。

Computational fluid dynamics (CFD) is increasingly being used in nuclear reactor safety (NRS) analyses to describe safety-relevant phenomena occurring in the reactor coolant system in greater detail. The majority of this paper is to investigate the CFD modeling and assessment for numerically simulating the thermal–hydraulic characteristics within the fuel rod bundle using CFD methodology. And this characteristic for mixing-vane grids of heat transfer capability and completeness has a great influence. The three-dimensional partial can reasonably reproduce distribution, it cannot simulate for traditional analysis tools and CFD can contribute at this ability.
This paper presents the results of numerical issues such as mesh refinement, wall treatment, are applied to the prediction of turbulent flow. The performance of various turbulence models are evaluated by calculation of the Nusselt number distribution in a fuel bundle. Comparison between numerical and experimental results of lateral and axial distributions for the Nusselt number obtained via turbulence model without near-wall functions is not sufficiently good, while agreement is found the realizable k-ε model with near-wall functions accurately predicts, for locations close to the support grid. As a result of this study, we have been able to determine the most appropriate turbulence models and the best enhanced wall treatment for modeling reactor coolant systems. Therefore, parallel tests or assistance are necessary for the regulator staff to review the license issues for CFD investigating the localized thermal-hydraulic characteristic within mixing-vane grids.

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