Void Fraction Characteristics and Flow Patterns of One-Component Gas-Liquid Two-Phase Flow

Abstract

The understanding of two-phase flow dynamics under microgravity is necessary to design a two-phase flow loop type thermal control system for space structures. Experiments at Japanese experiment module “KIBO” in the international space station are planned in 2015. In the ISS experiments, interface structures of gas-liquid two-phase flows at the just downstream of the heating section will be recorded by a high speed rate camera. One of the objects is to clarify the relationship between void fraction and flow pattern. In this paper, void fractions were measured by capacitance method to clarify two-phase flow characteristics of FC-72 which is used as the working fluid in the ISS experiment. Measured results of average void fraction agreed well with the correlations based on drift-flux model. On the other hand, flow pattern transitions agreed well with those by Mishima-Ishii' s equation. Moreover, from the mean square deviation in the probability distribution of measured void fraction, it is possible to classify flow patterns.