Flow Characteristics of Gas-Liquid Two-Phase Annular Flow under Microgravity : Experimental Results Utilizing a Drop Tower

Abstract

In order to predict various phenomena related to flow and heat transfer in space, it is necessary to carry out experiments under microgravity. The present work is concerned with the characteristics of gas-lipuid two-phase annular flow under microgravity condition utilizing a drop tower. The experiments were carried out in a vertical transparent acrylic tube of 10.5 mm I.D.and 200 mm length, using a mixture of gaseous nitrogen(GN₂)and water as the working fluid, in an annular flow region. The mean void fraction, pressure drop and liquid film thickness under microgravity were obtained and compared with the results of a ground test. It was found that the roughness of the liquid film surface was less and the mean liquid film thickness became greater under microgravity than under normal gravity.