Numerical simulation of subcooled boiling water at low pressure incorporating homogeneous MUSIG model

Abstract

Applying a three‐dimensional two‐fluid model coupled with homogeneous MUSIG approach, numerical simulations of subcooled water at low pressure were performed on the computational fluid dynamics code CFX‐10 with user defined FORTRAN program. A modified bubble departure diameter correlation based on the Unal semi‐mechanism model was developed. The water boiling flow experiments at low pressure in vertical concentric annulus from reference were used to validate the models. Good quantitative agreement with the experimental data is obtained, including the local distribution of bubble diameter, void fraction, axial liquid and vapor velocity. The results indicate that local bubble diameter first increases and then decreases due to the effect of bubble breakup and coalescence, and has the maximum bubble diameter along the radial direction. Moreover, the peak void fraction phenomenon in the vicinity of the heated wall is predicted at low pressure, which is developed due to the surface tension between vapor bubbles and heated wall.