An implicit numerical method for the three-dimensional two-fluid model with large phase changes in pressurized water reactors

IF 2.3 3区工程技术 Q1 NUCLEAR SCIENCE & TECHNOLOGY

Annals of Nuclear Energy Pub Date : 2025-09-18 DOI:10.1016/j.anucene.2025.111873

Na Young Song, Han Young Yoon

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Abstract

An implicit numerical method is proposed for solving the three-dimensional two-fluid model with a large phase, which is widely used in two-phase flow analysis of Pressurized Water Reactors (PWRs). The phase change process is implicitly modeled by coupling it with the pressure equation derived from the momentum and mass conservation equations. Simultaneously, the convection and diffusion terms of the governing equations are treated implicitly. To reduce the size of the system matrix, the computation procedure is divided into two separate steps: the “phase-link” step and the “space-link” step. This implicit scheme has been implemented in CUPID, a three-dimensional two-phase flow analysis code developed specifically for PWR applications. The present method was verified using a conceptual problem that simulates two-phase flow blowdown and refill phenomena occurring during a Loss of Coolant Accident (LOCA). The calculations demonstrated stability even with a large Courant–Friedrichs–Lewy (CFL) number. Subsequently, the implicit scheme was validated against the FLECHT-SEASET reflood experiment. The robustness and accuracy of the implicit scheme were confirmed by comparing the simulation results with experimental data across different CFL numbers. The differences between the results obtained at various CFL numbers were negligible.

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压水堆三维大相变双流体模型的隐式数值计算方法

提出了一种求解三维大相双流体模型的隐式数值方法，该方法在压水堆两相流分析中得到了广泛应用。通过将相变过程与由动量守恒方程和质量守恒方程导出的压力方程耦合，隐式地模拟了相变过程。同时，对控制方程的对流项和扩散项进行了隐式处理。为了减小系统矩阵的大小，将计算过程分为两个独立的步骤：“相链”步骤和“空间链”步骤。这种隐式方案已在丘比特，一个三维两相流分析代码开发专门为压水堆的应用实现。通过一个概念问题对该方法进行了验证，该问题模拟了在冷却剂损失事故（LOCA）中发生的两相流排污和再注现象。计算表明，即使在较大的Courant-Friedrichs-Lewy （CFL）数下也具有稳定性。随后，通过FLECHT-SEASET再驱实验对隐式方案进行了验证。通过对不同CFL数下的模拟结果与实验数据的比较，验证了隐式方案的鲁棒性和准确性。在不同CFL数值下得到的结果之间的差异可以忽略不计。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Annals of Nuclear Energy 工程技术-核科学技术

CiteScore

4.30

自引率

21.10%

发文量

632

审稿时长

7.3 months

期刊介绍： Annals of Nuclear Energy provides an international medium for the communication of original research, ideas and developments in all areas of the field of nuclear energy science and technology. Its scope embraces nuclear fuel reserves, fuel cycles and cost, materials, processing, system and component technology (fission only), design and optimization, direct conversion of nuclear energy sources, environmental control, reactor physics, heat transfer and fluid dynamics, structural analysis, fuel management, future developments, nuclear fuel and safety, nuclear aerosol, neutron physics, computer technology (both software and hardware), risk assessment, radioactive waste disposal and reactor thermal hydraulics. Papers submitted to Annals need to demonstrate a clear link to nuclear power generation/nuclear engineering. Papers which deal with pure nuclear physics, pure health physics, imaging, or attenuation and shielding properties of concretes and various geological materials are not within the scope of the journal. Also, papers that deal with policy or economics are not within the scope of the journal.