DOI: 10.1615/ICHMT.2012.ProcSevIntSympTurbHeatTransfPal
ISBN Print: 978-1-56700-302-4
ISSN: 2377-2816
Characterisation of downwards co-current gas-liquid annular flows
ABSTRACT
The hydrodynamic characteristics of downwards co-current two-phase (gas-liquid) flows inside a vertical tube (ID = 32 mm) have been investigated experimentally. Advanced optical techniques, namely Laser Induced Fluorescence and Particle Tracking Velocimetry, were utilised for the characterisation of these flows over a wide range of gas and liquid superficial velocities (UG = 0 − 34 m·s−1 and UL = 0.034 − 0.182 m·s−1), corresponding to Reynolds numbers ReG = 0 − 84,600 and ReL = 1,230 − 6,130. A flow regime map, which contains a previously unreported flow regime, is constructed based on the flow observations. The quantitative analysis of the liquid films allows the generation of film thickness, wave frequency, bubble size, bubble frequency and velocity profile data. It was found that the different observed flow regimes posses a characteristic combination of the investigated quantitative parameters. A model, based on modified mixing-length theory, was used to predict the liquid film velocity profiles and good agreement was found with the experimental results.