Abstract Recently, a Eulerian-based two-fluid computational fluid dynamics (CFD) framework with a wall heat flux partitioning approach has been intensively investigated for departure from nucleate boiling (DNB) simulation under the U.S. Department of Energy–funded Consortium for Advanced Simulation of Light Water Reactors (CASL) program. Understanding of the DNB characteristics over a range of pressurized water reactor–like operating conditions and accurate prediction of boiling crisis in the nuclear power system have been grand challenges because of the large impact of DNB on reactor safety and operational economics. The ultimate goal of this task in the CASL program is to introduce a robust multiphase CFD–based DNB modeling framework that is capable of characterizing an entire boiling history in which the wall boiling mode experiences the following through multiple stages of heat transfer mode: (1) single-phase convective heat transfer, (2) nucleate boiling heat transfer, and (3) identification of the departure of nucleate boiling. To validate the CASL boiling model, we have benchmarked simulated DNB over three different flow channel configurations (pipe flow, 5 × 5 fuel bundle with mixing vane tests, and 5 × 5 fuel bundle without mixing vane tests) against experimental measurements, and the validation result with open literature is reported. The DNB detection criteria in the simulation are checked by monitoring the peak wall temperature, wall dryout factor, and net energy balance. In addition to the DNB performance test, some preliminary sensitivity results on closure model selection are reported to address the prediction capability of local void profile against measurements. The boiling simulation tested in this study exhibits a maximum deviation of 24% from the measured DNB value in a high-pressure (i.e., 138 bars) subcooled pipe flow test. The ranges of operating conditions are as follows: 1650 to 2650 kg/m2·s for mass flux and 8.5 to 96 K for subcooled inlet temperature. The deviation is even reduced to 7% when the subcooled temperature is less than 40 K. Besides accuracy, base practice guidelines for DNB detection criteria are tested by monitoring three simulation variables: (1) maximum wall temperature, (2) wall dryout factor (i.e., K-value), and (3) energy balance. Numerical robustness of DNB simulation is largely achieved in most of the validation test except for a few high subcooled test cases.

中文翻译：

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使用选定的壁面沸腾封闭件在高压应用中模拟脱离核沸腾的进展

摘要 最近，在美国能源部资助的高级模拟联盟下，基于欧拉的双流体计算流体动力学 (CFD) 框架与壁热通量划分方法已被深入研究，以摆脱核沸腾 (DNB) 模拟。轻水反应堆 (CASL) 计划。由于 DNB 对反应堆安全和运行经济性的巨大影响，了解压水反应堆类似操作条件范围内的 DNB 特性以及准确预测核电系统中的沸腾危机一直是一项巨大的挑战。CASL 程序中此任务的最终目标是引入一个强大的基于多相 CFD 的 DNB 建模框架，该框架能够表征整个沸腾历史，其中壁沸腾模式通过多个传热模式阶段经历以下过程：（1 ) 单相对流传热，(2) 核沸腾传热，以及 (3) 核沸腾离开的识别。为了验证 CASL 沸腾模型，我们在三种不同的流道配置（管流、带混合叶片测试的 5 × 5 燃料束和不带混合叶片试验的 5 × 5 燃料束）上对实验测量的模拟 DNB 进行了基准测试，并验证报告了公开文献的结果。模拟中的 DNB 检测标准通过监测峰值壁温、壁干燥因子、和净能量平衡。除了 DNB 性能测试之外，还报告了一些关于闭合模型选择的初步敏感性结果，以解决局部空隙剖面对测量值的预测能力。本研究中测试的沸腾模拟与高压（即 138 巴）过冷管道流量测试中测得的 DNB 值的最大偏差为 24%。运行条件范围如下：质量通量为 1650 至 2650 kg/m2·s，过冷入口温度为 8.5 至 96 K。当过冷温度小于 40 K 时，偏差甚至降低到 7%。 除了准确性之外，DNB 检测标准的基本实践指南通过监测三个模拟变量进行测试：（1）最大壁温，（2）壁干燥因子（即 K 值），和（3）能量平衡。