A Study of the Flow Characteristics in Air-Water Two-Phase Flow under Microgravity : Results of Flight Experiments

Reliable design of space thermal management systems requires a through understanding of the hydrodynamic characteristics of two-phase flow influenced by the change in gravity. The data of flow patterns, void fraction, frictional pressure drop associated with its characteristics were obtained at normal gravity and in microgravity and hyper-gravity (2g) conditions aboard MU-300 aircraft capable of parabolic trajectory flying. Some experiments were performed for an air-water two-phase flow through 10 mm diameter adiabatic test section with 600 mm length of transparent acrylic resin horizontal tube. The results obtained at three gravity levels (μ.g, 1g and 2g) are compared with some of the existing flow pattern transition, void fraction and frictional pressure drop models and correlations. The gravity dependency of flow patterns was more clearly appeared with the decrease in gas and liquid flow rates. The effect of gravity on two-phase flow was insignificant for the turbulent flow regions.