Abstract This paper conducts high-resolution thermal hydraulic analysis of a Nuclear Thermal Propulsion (NTP) Fuel Element (FE) using a finite volume approach. Recent NTP design efforts have focused on using low-enriched uranium (LEU) fuel as an alternative to the historical highly-enriched uranium (HEU) fuel. In addition to changing materials’ properties, variations in dimensions and flow characteristics are also considered. This makes the applicability of legacy experimental data questionable for the new LEU designs, as the data was generated for a specific range of design characteristics. Nowadays, there is limited accessibility to experimental capability under realistic hot hydrogen conditions. However, some experimental setups could be replaced or complemented by higher-order numerical analysis, which is the end objective of the computational framework developed here. This study implements a 3D conjugate heat transfer (CHT) numerical solver between solid and fluid regions using OpenFOAM Computational Fluid Dynamic (CFD) toolbox. The hydrogen flow in the fluid region is simulated using Reynolds-averaged Naiver-Stokes (RANS) model, while the solid region is modeled using a conduction heat transfer solver. The 3D simulation results are validated against experimental data obtained from the Nuclear Engine for Rocket Vehicle Application (NERVA) Nuclear Rocket Experimental (NRX) A6 program. The latter shares similar design parameters with modern NTP systems, such as dimensions and flow conditions. In addition, legacy heat transfer correlations were implanted in a reduced-order 1.5D semi-analytic solution, and the results were compared against the OpenFOAM solution. The results presented in this paper conclude that OpenFOAM can serve as a high-resolution thermal hydraulic code both for reproducing legacy experiments and educating reduced-order models.

中文翻译：

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使用 OpenFOAM 对核热推进燃料元件进行高分辨率热分析

摘要 本文使用有限体积方法对核热推进 (NTP) 燃料元件 (FE) 进行高分辨率热水力分析。最近的 NTP 设计工作集中在使用低浓缩铀 (LEU) 燃料作为历史高浓缩铀 (HEU) 燃料的替代品。除了改变材料的特性外，还考虑了尺寸和流动特性的变化。这使得旧实验数据对新 LEU 设计的适用性存在问题，因为数据是针对特定范围的设计特征生成的。如今，在现实的热氢条件下，实验能力的可及性有限。然而，一些实验设置可以被高阶数值分析取代或补充，这是这里开发的计算框架的最终目标。本研究使用 OpenFOAM 计算流体动力学 (CFD) 工具箱在固体和流体区域之间实现了 3D 共轭传热 (CHT) 数值求解器。流体区域中的氢流动使用雷诺平均 Naiver-Stokes (RANS) 模型进行模拟，而固体区域使用传导热传递求解器进行建模。3D 模拟结果根据从火箭车辆应用核发动机 (NERVA) 核火箭实验 (NRX) A6 计划获得的实验数据进行验证。后者与现代 NTP 系统共享类似的设计参数，例如尺寸和流动条件。此外，在降阶 1.5D 半解析解中植入了传统的传热相关性，并将结果与​​ OpenFOAM 解决方案进行比较。本文中提出的结果得出结论，OpenFOAM 可以作为高分辨率的热力水力代码，用于重现传统实验和教育降阶模型。