EXPERIMENTAL INVESTIGATION OF STEAM-WATER ANNULAR FLOW IN PIPING JUNCTIONS.

The characteristics of dividing annular steam-water flow in horizontal tee junctions with horizontal branches have been investigated experimentally. A separated flow axial momentum balance was used to correlate the pressure recovery data in the run of the tee. The pressure recovery coefficient was approximately unity independent of the inlet flow conditions, flow split ratio and branch size. A model, based on a mechanical energy balance was used to define a two-phase loss multiplier for the branch. For the range of data tested, this multiplier was found to be independent of inlet conditions. Empirical correlations were developed as a function of flow split ratio for the branch to inlet diameter ratios tested. Through the set of measurements made in the present work, the pressure change and phase separation characteristics were shown to be strongly interdependent. The implications of this phenomena are very important in analysing nuclear reactor thermal-hydraulics during a postulated loss of coolant accident and in the oil industry where steam from a common header carrying a high quality steam-water mixture is injected into oil wells to enhance the recovery process.