Numerical simulation of flooding characteristics in steam-water countercurrent inside an inclined pipe under condensation conditions

Abstract

In this paper, a three-dimensional CFD model, which is established on VOF (Volume of Fluid) model, Lee model together with CSF (Continuum Surface Force) model and RNG k − ɛ turbulence model, is adopted for the condensation heat and mass transfer of steam in an inclined circular tube with the occurrence of flooding and liquid bridge. The entire process of liquid bridge formation is depicted with a three-dimensional space-time plot of the wave amplitude of the interfacial wave with time and axial distance. The effects of different pipe inclination angles and different contact angles on the flow behavior and heat transfer characteristics are investigated and the results demonstrate that under high liquid film Reynolds number and condensation conditions, as the inclination angle increases, the liquid bridge begins to form at a position which moves upward along the pipe. The reason is that as the inclination angle increases, the liquid film is more uniformly distributed in the radial direction, and a vortex symmetrical about the axis is formed on the leeward side of the flooding wave.