Generation of Air–Water Two-Phase Flow Patterns by Altering the Helix Angle in Triple Helical Microchannels

Abstract

Flow of a liquid inside a helical tube is composed of axial and circumferential components, the latter arising because of its specific geometry. For a gas–liquid two-phase flow inside a helical tube, the coupled effect of these two flow components leads to a variety of flow patterns, for example, slug, bubble, and stratified flow. We present here a novel triple-helical microchannel, in which, the two-phase flow is found to engender several additional flow patterns not observed with the conventional geometries, for example, the parallel and oscillating annular flow and even simultaneous occurrence of several such patterns. We show that the transition between these patterns depends not only on the fluid rates of the two liquids but also on the helix angle. We have presented detailed phase diagrams to elaborate these effects. We have examined also the effect of channel geometry on the specific features of these flow patterns.