Detailed Characterization of Two-Phase Annular Flow in a Horizontal Tube

Abstract

In this study, non-intrusive pressure drop, liquid film thickness distribution and wave behavior measurements have been obtained for 140 and 220 two-phase flow conditions in horizontal 8.8 mm I.D and 15.1 mm I.D. tubes, respectively. Horizontal flow regimes ranging from stratified-wavy to annular were studied in long clear test sections. Pressure drop data appeared to show different trends for the wavy, wavy-annular and annular flow regimes, suggesting that a unique model may be required for each. In addition, wave frequency showed clearly different behavior for these regimes, with only minor liquid flow dependence in the wavy and wavy-annular flows and strong liquid flow dependence in annular flow. Interestingly, disturbance wave velocity could be correlated to within 10% by the gas friction velocity in the annular regime and within 20% in the wavy-annular regime, leading to a simple correlation between pressure drop and wave velocity. Base film thickness data (between waves) show that the film is relatively insensitive to gas flow at the side and top of the tube and that the film thickness around the tube becomes nearly independent of liquid flow rate at high gas flows. Empirical correlations of the various data sets are presented with the goal of aiding general horizontal two-phase flow modeling efforts.