Simulation of Subcooled Boiling in Multiphase CFD Code CFX

29th Symposium of AER on VVER Reactor Physics and Reactor Safety (2019, Energoland, Mochovce NPP, Slovakia)
[6] nuclear applications of computational fluid dynamics (CFD)


Ladislav Vyskočil, Václav Železný and Pavel Zácha


This paper presents a validation of multiphase CFD code Ansys CFX 18 on selected experiments with subcooled boiling flow. Ansys CFX code can simulate multiphase flow by solving three balance equations for each phase (Euler-Euler approach). Boiling on the heated wall can be simulated with the model proposed by Kurul and Podowski. A set of mathematical models of physical phenomena in boiling bubbly flow was selected and tested on the following experiments with subcooled boiling: DEBORA experiments, ASU experiments, Bartolomej et al. experiment and FRIGG experiment. The DEBORA experiment is a vertical pipe with heated wall. The working fluid is freon R-12. The ASU boiling experiment is a vertical annular channel with heated inner wall and freon R-113. The Bartolomej experiment is a vertical heated pipe with boiling water. The FRIGG experiment is a vertical channel with 5 heated rods and boiling water. It was found out that CFX code can reasonably reproduce measured data in all these experiments. At the end of this paper we present an application of this modelling approach to the real case with a complicated geometry: simulation of subcooled boiling in the VVER-1000 fuel assembly with bent rods. The presented work was carried out within the Technology Agency of the Czech Republic (TA ČR) project TH02020360 „Modeling of the critical heat flux with computational fluid dynamics codes“.