Two-phase flow patterns and transitions in a small, horizontal, rectangular channel

Abstract

Horizontal two-phase flow was studied in a small cross-sectional-area (19.05 × 3.18 mm) rectangular channel with both the short and long sides forming the base, resulting in aspect ratios of 6 and 1 6 , respectively. Adiabatic flows of air/water mixtures were tested over a large mass flux range (50–2000 kg/m 2 s). The full quality range was considered whenever experimentally achievable. Flow patterns were established and both mean and dynamic pressure measurements were used to accurately establish the plug/bubble-to-slug flow transition. This result, together with visual observations and supplemented with photographic data, was used to develop flow pattern maps. A comparison of existing flow pattern maps for circular pipes, capillary tubes and larger rectangular channels led to the conclusion that, while qualitative agreement exists, these maps are not generally applicable to the subject small rectangular channel on the quantitative basis.