STEAM-WATER STRATIFIED FLOW IN T-JUNCTIONS – EXPERIMENTS AND MODELLING

Experimental data on dividing steam-water two-phase stratified flow in T-junctions with horizontal inlet and both horizontally and vertically downward branches are presented in this paper. The measurements included inlet liquid level and run and branch fully developed void fraction. These measurements were used to describe the effects of the inlet flow conditions and junction geometry (relative branch diameter and orientation) on phase redistribution. The data covered the range of inlet steam and water superficial velocities from 1.5 to 5.0 m/s and 0.05 to 0.09 m/s respectively. Under these conditions, which have not been previously examined, the extent of phase redistribution was greatly affected by the inlet superficial gas velocity (u GS ), and the junction geometry. The effect of inlet superficial water velocity (u LS ) on the redistribution characteristics was less significant for the range of data tested. A model for the phase redistribution of stratified flow in T-junctions is developed. It consists of two submodels accounting for the distribution in the main inlet pipe and for phase redistribution in the junction. The model was found to be able to predict the data for smooth stratified flow very well. For wavy inlet flow, the model overpredicted the phase separation data.