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

Abstract

In order to better understand the effect of gravity on two-phase flow, the microgravity experimental tests were conducted aboard MU-300 aircraft capable of parabolic trajectory flying. They are carried out in an air-water two-phase flow through 10 mm diameter adiabatic test section, which is 600 mm lengths of transparent acrylic resin horizontal tube. The obtained experimental data covered a range of liquid and gas flow rates with the liquid superficial velocity ranging from 0.095 m/s to 2.56 m/s, and the gas superficial velocity ranging from 0.032 m/s to 21.08 m/s. Flow pattern results obtained under μg, 1 g and 2 g conditions were compared with void fraction based flow pattern transition models developed by Bousman (1995). The effects of the gravity change on flow patterns were significantly large at low gas and liquid superficial velocities. In the comparisons of the microgravity void fraction results with the correlation proposed by Inoue-Aoki (1970), it was found that the micorgravity void fraction was greater than the model as 42% for bubbly flow region. Two-phase frictional pressure drops obtained under three g-levels were compared with each other, and it was also found that frictional pressure drop were well fitted with the Lockhart-Martinelli-Chisholm model. The effect of gravity change on the pressure drops was insignificant for the turbulent flow reginos.