Numerical simulation and experimental validation of flow characteristics for a butterfly check valve in small modular reactor

The butterfly check valve is widely used in small modular reactors to prevent pumps from being damaged by backflow during normal operating conditions. However, the large flow resistance of the valve has an important impact on the flow characteristics of the reactor coolant system during natural circulation state. The present study aims to perform and validate a series of simulations of the flow characteristics for a butterfly check valve in a small modular reactor employing the computational fluid dynamics (CFD) method. Steady state simulations were first performed to obtain the relationship between the valve loss coefficient and the valve opening angle. Based on dynamic mesh techniques, transient state simulations with five different turbulence models, standard k-epsilon model, RNG k-epsilon model, realizable k-epsilon model, SST k-omega model, and BSL-RSM model, were applied to obtain valve loss coefficient and valve flow coefficient respectively. Furthermore, experiments were carried out and compared with the results of transient numerical simulations. It must be pointed out that compared to other turbulent models, the simulation results using the standard k-epsilon model agree better with the experiment results. The experimental and numerical results show that the numerical simulation methodology established in this paper can be used to obtain the valve flow coefficient when a small modular reactor is under natural circulation conditions, and the coefficient can be used to accurately analyze the natural circulation characteristics of small modular reactors.

Automated summary

This study performed simulations and validations of the flow characteristics for a butterfly check valve in a small modular reactor using computational fluid dynamics (CFD) method. The results showed that the simulation results using the standard k-epsilon model agreed better with the experiment results, indicating the accuracy of this model in analyzing the natural circulation characteristics of small modular reactors.