Local Liquid Velocity Measurements In Horizontal Annular Two Phase Flow

Annular Two-Phase Flow presents the wide range of industrial applications of annular two-phase flow regimes. This book discusses the fluid dynamics and heat transfer aspects of the flow pattern. Organized into 12 chapters, this book begins with an overview of the classification of the various types of interface distribution observed in practice. This text then examines the various regimes of two-phase flow with emphasis on the regions of occurrence of the annular flow regime. Other chapters consider the single momentum and energy balances, which illustrate the differences and analogies between single- and two-phase flows. This book discusses as well the simple modes for annular flow with consideration to the calculation of the profile of shear stress in the liquid film. The final chapter deals with the techniques that are developed for the measurement of flow pattern, entrainment, and film thickness. This book is a valuable resource for chemical engineers.

A IUTAM symposium on "Measuring Techniques in Gas-Liquid Two Phase Flows" was held on July 5-8, 1983 in Nancy, France. This topic in cluded instrumentation for steam-water and liquid-vapor flows but strictly excluded measuring techniques for gas or liquid flows with solid particles. The top priority in the paper selection was given to presentations of new methods which had been substantiated by theoretical modeling, calibration tests and comparison tests with other techniques. Examples of experimental resul ts obtained with the proposed instrumentation had to be displayed. However the interpretation of these results in terms of two-phase flow or heat transfer modeling did not fall wi thin the scope of the meeting. Thirty four papers were presented during the Symposium and 79 participants coming from Canada, European countries, Japan and the United States attended the sessions. They represented not only Universities but also state agencies and private companies. After the meeting each paper was peer-reviewed by at least three referees. The Editors of this Procee dings Volume are pleased to extend their deep gratitude to the following reviewers: J.L. Achard, R.J. Adrian, B. Azzopardi, J.A. Boure, G. Costigan, M. Courtaud, A.E. Dukler, F. Durst, J.R. Fincke, G. Gouesbet, P. Griffith, T.J. Hanratty, A. Hawighorst, T.R. Heidrick, G. Hetsroni, Y.Y. Hsu, M.

The effect of pipe diameter on horizontal annular flow is examined. Measurements of the local film height, the local droplet flux, the local velocity, and the entrained fraction for annular flow in a 9.53 cm horizontal pipe have been obtained. The measurements are compared with the results from previous investigators for horizontal annular flow in pipes with diameters of 2.54 cm and 5.08 cm. A new large scale two-phase flow facility has been designed and constructed. The facility has the ability to incline a 26.5 m pipe at angles between positive and minus 2.5 degrees from the horizontal. Local film height measurements show that the film distribution becomes increasingly asymmetric with increasing pipe diameter. The effect of pipe diameter on the asymmetries of the liquid film distribution is predicted approximately by a Froude number. At Froude numbers below 50, the liquid is stratified as a pool at the pipe bottom. A turbulent diffusion model developed by a co-researcher for the droplet concentration distribution is in good agreement with measurements at low gas velocities and low droplet concentrations. At higher droplet concentrations, velocity measurements suggest the existence of a secondary flow in the gas which inhibits droplet settling. Entrainment correlations developed from experiments in small diameter pipes, over predict the entrained fraction in large diameter pipes. A generalized entrainment correlation based on an equilibrium rate balance between the rate of atomization of droplets from the liquid film and the rate of deposition of droplets back to the liquid film is developed. The correlation is easily interpreted for two extremes of the liquid film distribution. When the film is distributed uniformly around the pipe wall, the entrainment relation reduces to a form developed by previous researchers. For conditions where the liquid film is stratified as a pool at the pipe bottom, a new entrainment relation is developed which is in good agreement with the results.