Abstract Nuclear reactor containment flows are primarily driven by density differences in the long term of a severe accident. It is crucial to predict such flows from the perspective of reactor safety. The present work addresses the assessment of open-source CFD code OpenFOAM in modelling buoyancy-driven turbulent flows and heat transfer relevant for analyzing the flow and mixing in a nuclear reactor containment during severe accident scenarios. A fully compressible solver with the k - ω based shear stress transport (SST) turbulence model was utilized to simulate the two-dimensional turbulent flow of a differentially heated square cavity(h ~ 0.75, Ra ~ 10 9 ) and then against the technical scale THAI-TH21 natural convection test (60 m 3 , h ~ 9 m, Ra ~ 10 12 ). The results from the current study, emphasize the importance of considering radiation phenomenon in buoyancy-driven flows and the grid resolution needed in the near-wall region to accurately predict wall heat flux. Overall, the simulation results of time-averaged temperature and velocity profiles in the quasi-steady state compare very well with experimental data. The predicted values of external wall heat transfer rates on the THAI vessel, the convective wall heat flux in the gas region, and the impact of buoyancy on turbulence are discussed.

中文翻译：

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与核反应堆安全相关的外壳中浮力驱动流动的 CFD 建模

摘要 核反应堆安全壳流动主要是由严重事故的长期密度差异驱动的。从反应堆安全的角度预测此类流量至关重要。目前的工作涉及评估开源 CFD 代码 OpenFOAM 在建模浮力驱动的湍流和传热方面，这些与分析严重事故情景期间核反应堆安全壳中的流动和混合有关。使用基于 k - ω 的剪切应力传输 (SST) 湍流模型的完全可压缩求解器来模拟差热方腔 (h ~ 0.75, Ra ~ 10 9 ) 的二维湍流，然后针对技术规模THAI-TH21 自然对流测试（60 m 3 ，h ~ 9 m，Ra ~ 10 12 ）。从目前的研究结果来看，强调考虑浮力驱动流中辐射现象的重要性以及近壁区域所需的网格分辨率以准确预测壁面热通量。总体而言，准稳态下时均温度和速度分布的模拟结果与实验数据非常吻合。讨论了 THAI 容器外壁传热率的预测值、气体区域的对流壁热通量以及浮力对湍流的影响。