Abstract In this paper coupled calculations with the CFD code ANSYS-CFX-19.0 and the Monte Carlo neutronics code MCNP6 were performed to analyze the heat transfer in supercritical water flowing through the typical fuel assembly of the high-performance light water reactor (HPLWR), in order to improve the characterization of the heat transfer phenomena in supercritical water under non-uniform axial heat flux distributions that is characteristic of this type of reactor. To check the capability of the CFX model to predict the thermal-hydraulic behavior of supercritical water, the computational results were compared with two experimental data. The Shitsmans experiment in the presence of heat transfer deterioration (HTD) using four low-Re turbulence models (SST, k- ω , BSL-k- ω , and ω -Reynolds Stress) and the Wanǵs experiment in absence of HTD, using the low-Re-SST and the scalable-wall-function-SSG turbulence models. In the presence of the HTD phenomenon, results showed the high dependency of the wall temperature with the turbulence model and the turbulent Prandtl number selected. In the absence of HTD, both turbulence models studied adequately predicted the behavior of the wall temperature distribution. For the coupled neutronic/thermal-hydraulic analysis of the typical HPLWR fuel assembly, the low-Re SST turbulence model and the Prt = 1.5 were used. Different axial profiles of heat flux generated in the fuel rods were obtained for the different power values studied. For the analyzed conditions, the presence of HTD in the lower zone of the fuel assembly was observed. In addition, the results showed a strong non-uniformity of the circumferential surface cladding temperature distribution in the sub-channel located at the corner of the fuel assembly; a new curvature radius of the assembly box corner was proposed to obtain a well homogenized circumferential wall temperature distribution.

中文翻译：

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超临界水反应堆燃料组件传热现象的耦合蒙特卡罗-CFD分析

摘要 本文采用 CFD 代码 ANSYS-CFX-19.0 和蒙特卡罗中子学代码 MCNP6 进行耦合计算，分析流过高性能轻水反应堆（HPLWR）典型燃料组件的超临界水的传热，为了改善这种类型反应堆在非均匀轴向热通量分布下超临界水中的传热现象的表征。为了检查 CFX 模型预测超临界水的热工水力行为的能力，将计算结果与两个实验数据进行了比较。使用四种低 Re 湍流模型（SST、k-ω、BSL-k-ω 和 ω-雷诺应力）在存在传热恶化 (HTD) 的情况下的 Shitsmans 实验和没有 HTD 的 Wanǵs 实验，使用低 Re-SST 和可伸缩壁函数-SSG 湍流模型。在存在 HTD 现象的情况下，结果显示壁温与湍流模型和湍流普朗特数的高度相关性。在没有 HTD 的情况下，研究的两种湍流模型都充分预测了壁温分布的行为。对于典型 HPLWR 燃料组件的中子/热工水力耦合分析，使用了低 Re SST 湍流模型和 Prt = 1.5。对于所研究的不同功率值，获得了在燃料棒中产生的热通量的不同轴向分布。对于所分析的条件，观察到燃料组件下部区域中存在 HTD。此外，结果表明，位于燃料组件拐角处的子通道中圆周表面包覆温度分布存在强烈的不均匀性；提出了新的装配盒角的曲率半径，以获得均匀的周壁温度分布。