Prediction of Thermal-Hydraulic Parameters in Rod Bundle Assembly Domain Based on Similarity Features
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摘要: 为准确预测高雷诺数、复杂结构下堆芯流域的热工水力参数,并提高神经网络的预测精度,以快速获悉堆芯热工水力状态,本研究提出了一种新的辅助预测方法。通过对不同工况下棒束通道精细化计算结果进行分析,确定了棒束组件热工水力宏观参数与精细参数分布之间的相似性规律,并以此规律构建神经网络的输入信息,以精确预测温度、压力及速度参数。研究结果表明,本文所构建的代理模型在宏观参数测试数据上的最大均方误差为7.86×10−4,最小均方误差为1.39×10−4;在精细参数测试数据上的最大均方误差为9.39×10−3,最小均方误差为5.20×10−4,表明该模型能够准确预测堆芯的热工水力状态。此外,该代理模型在0.504 s内获取堆芯精细化热工水力参数场,数据获取效率较传统方法提升了1149倍,可为构建反应堆堆芯数字孪生体提供有效技术支持。Abstract: To accurately predict the thermal-hydraulic parameters of reactor core flow domains under high Reynolds numbers and complex geometries, and to enhance the predictive accuracy of neural networks for rapid assessment of core thermal-hydraulic conditions, this study proposes a novel auxiliary prediction method. An analysis of detailed simulation results of rod bundle channels under various operating conditions identified a similarity pattern between the macroscopic thermal-hydraulic parameters of the rod bundle assemblies and the distribution of fine-scale parameters. This pattern was then utilized to construct the input features of the neural network, enabling precise predictions of temperature, pressure, and velocity parameters. The results demonstrate that the developed surrogate model achieves a maximum mean squared error (MSE) of 7.86×10−4 and a minimum MSE of 1.39×10−4 on macroscopic parameter test data. For fine-scale parameter test data, the maximum and minimum MSE are 9.39×10−3 and 5.20×10−4, respectively, indicating the model’s high accuracy in predicting core thermal-hydraulic conditions. Moreover, the surrogate model obtains fine-scale thermal-hydraulic parameter fields of the core within 0.504 seconds—an efficiency improvement of 1149 times compared to traditional methods. This provides a powerful technical foundation for developing digital twins of nuclear reactor cores.
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Key words:
- Rod bundle channel /
- Thermal-hydraulic /
- Machine learning /
- Similarity
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表 1 组件边界
Table 1. Boundary of the Component
参数 参数值 压力/MPa 15.5 入口温度/℃ 292.8 入口平均速度/(m·s−1) 4.06 平均热流密度/(W·m−2) $ 8.447\times {10}^{5}\mathrm{sin}\left(\dfrac{{\text{π}}{\textit{z}}}{3.75}\right) $ z—轴向位置,m。 表 2 误差表
Table 2. Error Results
参数 宏观参数 精细参数 训练数据 测试数据 训练数据 测试数据 横流速度误差 1.16$ \times $10−4 7.86$ \times $10−4 3.40$ \times $10−3 5.19$ \times $10−3 温度误差 1.18$ \times $10−4 1.39$ \times $10−4 4.97$ \times $10−3 9.39$ \times $10−3 压力误差 5.46$ \times $10−5 2.52$ \times $10−4 5.70$ \times $10−4 5.20$ \times $10−4 -
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