Steam-water annular flow in a horizontal dividing T-junnction

The results of an experimental investigation of the separation phenomena in dividing steam-water annular flow in a horizontal T-junction are presented. Measurements included the pressure and void fraction distributions as well as the total flow rate and quality along the inlet and branching legs. A detailed set of experiments were performed enabling the effects of flow split, inlet quality and inlet mass flux on the phase separation and pressure characteristics to be determined. For the annular inlet flow conditions considered herein, total separation was approached when more than 30% of the inlet flow was removed through the branch. At lower branch flow rates, the degree of phase separation was strongly dependent on the branch flow split and inlet quality. The pressure change from the inlet through the run of the T-junction was modelled using an axial momentum balance at the junction for both homogeneous and separated flow assumptions. The separated flow momentum correction factor was found to be distributed around a value of unity indicating that the axial momentum carried by the branching flow was relatively insignificant. The pressure change from the inlet through the branch was modelled using a balance of mechanical energy for the branching flow which consisted of reversible and irreversible components. Accordingly, a two-phase branch loss multiplier was defined and found to be dependent upon the flow split ratio and junction geometry but independent of the inlet conditions.