Numerical analysis for slugging of steam-water stratified two-phase flow in horizontal duct

Thermalhydraulic transient phenomena of a steam-water two-phase flow was calculated numerically in order to investigate the onset of slugging from a stratified flow in a horizontal duct. Conservation equations were solved by the finite difference method using a two-phase flow analyzer ‘MINCS’. The analysis was performed to investigate the initiation of slugging with and without phase change, or condensation. The present instability criteria for the onset of slugging with no condensation agreed well with that of the Mishima–Ishii relation while it was much lower than that defined by the Kelvin–Helmholtz instability criteria. However, as the temperature difference between phases increased, steam velocity became higher for the onset of slugging condition. The characteristics of flow reversal and water hammering which were the consequences of slugging with condensation, were investigated and described. It is expected that this modeling could be well applied to complicated thermalhydraulic phenomena accompanied by flow reversal and water hammering in power plants.