Distribution of Local Void Fraction of Air-Water Two-Phase Flow in a Vertical Channel

Abstract

The present report describes an experimental study on the distributions of local void fraction along a cross section of a vertical channel in fully developed air-water two-phase flow at atmospheric presure, using a probe method. In bubble flow, a peculiar distribution which was fundamentally different from a power law distribution accepted in previous studies was observed. It had a peak of void fraction near the wall. The position of the maximum void fraction was at (0.5∼0.7)d from the wall where d was a bubble major axis. The authors proposed an empirical formula which was in good agreement with the present and another experimental results and applicable not only to bubble flow but also to slug flow. Comparisons between this formula and previous formulas were made in the experimental results.