FLOW STRUCTURE OF DEVELOPING STEAM-WATER TWO-PHASE FLOW IN A LARGE-DIAMETER PIPE

摘要

The flow structure of steam-water two-phase upward flow was measured in a vertical pipe 155 mm in diameter. Experiments were conducted under volumetric flux conditions of J{sub}G < 0.25 m/s and J{sub}L < 0.6 m/s. The radial distribution of void fraction, bubble chord length and gas velocity were obtained by traversing optical dual void probes in the pipe. Flow in the pipe reached a quasi-steady state within the vertical distance of H/D = 6. The correlation of local mean bubble diameter was derived as a function of local void fraction and pressure. With this correlation, cross-sectional averaged bubble diameter was predicted with high accuracy compared to the existing constitutive equation which is mainly used in best-estimate codes.