Nonlinear Reduced-order Analysis of Three-dimensional Thermal Stratification in the Upper Plenum of Lead-bismuth Cooled Fast Reactor Based on Graph Neural Network
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摘要: 铅铋快堆上腔室的热分层现象对堆内构件的结构安全性和系统余热排出能力具有重要影响,需重点分析。本文首先基于计算流体动力学(CFD)程序FLUENT得到铅铋快堆上腔室热分层现象的高精度全阶快照,然后利用图神经网络(GNN)构建的图自编码器(GAE)对快照进行非线性降阶,并将非线性降阶后的重构结果与本征正交分解(POD)的线性降阶结果进行对比分析,最后通过结合多层感知机对热分层快照开展在线状态识别与预测分析。结果表明,由于GNN具有高度的非线性,使其在大规模CFD数据的非线性降阶方面具备独特优势,其1阶模态重构精度与POD的30~50阶基函数的重构精度相当;在在线阶段,以472 ms的时长即可完成对热分层快照的特征识别和预测,且预测精度与直接重构精度相近。相关研究成果可为铅铋快堆热分层现象演化机理分析及后果预测提供新的分析方法支撑。
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关键词:
- 铅铋快堆 /
- 热分层 /
- 非线性降阶 /
- 图神经网络(GNN) /
- 本征正交分解(POD)
Abstract: The thermal stratification phenomenon in the upper plenum of the lead-bismuth fast reactor has significant implications for the safety of internal components and the ability to remove residual heat. This paper focuses on analyzing this phenomenon. Firstly, high-precision full-order snapshots of the thermal stratification in the upper plenum of the lead-bismuth fast reactor are obtained using the computational fluid dynamics software FLUENT. Then, the graph neural network (GNN) is employed to construct a graph autoencoder (GAE) for nonlinear order reduction of the snapshots, and the reduced reconstruction results are compared with the linear reduction results obtained using Proper orthogonal decomposition (POD). Finally, a multilayer perceptron is used for online state recognition and predictive analysis of the thermal stratification snapshots. The research results demonstrate that the graph neural network, due to its high level of nonlinearity and its inherent advantage in nonlinear order reduction of large-scale CFD data, achieves comparable first-order modal reconstruction accuracy to that of POD with 30~50 basis functions. During the online process, the feature recognition and prediction of thermal stratification snapshots can be completed within a duration of 472 ms, with accuracy similar to the reconstruction accuracy. The related research results can provide a new analytical method support for the evolution mechanism analysis and consequence prediction of thermal stratification phenomenon in lead-bismuth fast reactors. -
表 1 结构参数和实验参数数据
Table 1. Structural Parameters and Experimental Data
参数名 实验设计数据 ABTR数据 比值 上腔室高度/m 1.20 8.02 0.15 出口高度/m 0.8000 5.347 0.15 上腔室直径/m 0.3147 4.910 0.065 中间构件直径/m 0.1455 2.270 0.065 入口直径/m 0.0127(×3个) 0.3710(×3个) 0.009 出口直径/m 0.0160(×2个) 非保护性事故流量/(m3·s−1) 0.001429 0.3775 0.0038 堆芯冷却剂流速/(m·s−1) 3.759 0.296 12.7 腔室热流体温度/℃ 300 575 0.52 腔室冷流体温度/℃ 250 525 0.48 佩克莱数(Pe) 1616 12520 0.13 雷诺数(Re) 28349 788237 0.04 Ri 1616 1616 1 -
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