堆芯瞬态核热耦合数值稳定性研究

Research on Numerical Stability of Transient Neutronics/Thermal-Hydraulic Coupling in Reactor Core

本文基于格林函数节块法程序TNGFM与子通道程序COBRA-EN开发了三维瞬态核热耦合计算程序,利用压水堆弹棒算例对核热耦合数值稳定性进行了分析,并提出了改进Picard迭代方法。数值模拟结果表明,减小计算时间步长可提高耦合计算数值稳定性,但计算效率较低,在物理计算外迭代中引入近似反馈可有效提高耦合收敛性能并大大减少耦合计算迭代次数。

A three-dimensional transient neutronics/thermal-hydraulics coupling calculation program is developed based on Green’s function nodal method program TNGFM and subchannel thermal-hydraulic analysis program COBRA-EN.The numerical stability of neutronics/thermal-hydraulics coupling is analyzed with a PWR rod ejection example and an improved Picard method is proposed.The numerical simulation results show that reducing the time step can improve the numerical stability of coupling computation with a low efficiency.Introducing approximate feedback into external iteration of neutronics can effectively improve the coupling convergence performance and greatly reduce the number of iterations of coupling computation.