Sampling probe studies of the gas core in annular two-phase flow-I The effect of length on phase and velocity distribution

Abstract

Mass velocity distributions have been measured in air/water mixtures flowing upwards in a 1 1 4 in. I.D. vertical tube, at about ′1 1 2 atm pressure. A traversing probe was used to measure impact pressure and to extract samples at a number of stations. The water was introduced at the wall through a porous sinter so that all spray arose from entrainment; studies were made of the build-up of spray and changes in its distribution with distance. Entrainment was still increasing at 17 1 2 ft from the injector. The presence of the water film, even before any substantial entrainment, changed the gas velocity profile from the normal flat-topped form for turbulent flow to a sharply peaked from; this profile proved, on analysis, to follow the form of the classical velocity deficiency law for a very rough surface, but with a new value for the coefficient of the logarithmic term. Film thickness and pressure drop data are presented and are included in the analysis. © 1963.