Effects of a Flow Obstacle on the Deposition Rate of Droplets in Annular Two-Phase Flow

Abstract

Double film extraction technique was used to elucidate the effects of a flow obstacle on the deposition rate of droplets in annular two-phase flow. In the present experiments, the test section was a round tube of 5 mm in inside diameter, air and water were used as test fluids and the flow direction was vertical upward; a short tube that was 2 mm in inside diameter, 3 mm in outside diameter and 20 mm in length was used as a flow obstacle. It was shown that the deposition rate of droplets was markedly increased if the present flow obstacle was concentrically placed in the flow channel. In all the experimental conditions tested, the deposition rates when the flow obstacle was placed were approximately 1.5 times larger than the deposition rates when no obstacle was placed. An empirical correlation was developed to elucidate the influence of flow parameters on the enhancement of deposition rate by the present flow obstacle of simple geometry.