Motion of a gas slug in inclined tubes

Abstract

The velocities of a freely rising gas slug and a phase boundary (gas-liquid) under conditions of liquid discharge in tubes of various diameters are experimentally studied. It is shown that the nonmonotonic character of the dependence of measured velocities on the angle of inclination is determined only by the curvature in the vicinity of the critical point of the head of the slug or the phase boundary during liquid discharge. Experimental results are obtained by measuring the profiles of curvature of the bubble head in mutually perpendicular planes. For these purposes, an appropriate computer program was developed, and an immersion optical procedure was used that made it possible to eliminate optical “noises” associated with the thickness of a tube wall.