Two‐phase flow, thermal management systems are currently being considered as an alternative to conventional, single phase systems for future space missions because of their potential to reduce overall system mass, size, and pumping power requirements. Knowledge of flow regime transitions, heat transfer characteristics, and pressure drop correlations is necessary to design and develop two‐phase systems. This work is concerned with microgravity, two‐phase flow pressure drop experiments. The data are those of a recent experiment (Hill and Best 1990) funded by the U.S. Air Force and conducted by Foster‐Miller in conjunction with Texas A&M University. A boiling and condensing experiment was built in which R‐12 was used as the working fluid. A Foster‐Miller two phase pump was used to circulate a freon mixture and allow separate measurements of the vapor and liquid flow streams. The experimental package was flown five times aboard the NASA KC‐135 aircraft which simulates 0‐‘‘g’’ conditions by its parabolic flight trajectory. Test conditions included stratified and annual flow regimes in 1‐‘‘g’’ which became bubbly, slug or annular flow regimes in 0‐‘‘g’’.
A portion of the current work outlines a methodology to analyze data for two‐phase, 0‐g experimental studies. A technique for correcting the raw pressure drop data collected from the test package is given. The Corrected pressure drop measurements are compared with predictive model. The corrected pressure drop measurements show no statistically significant difference between the 1‐‘‘g’’ and 0‐‘‘g’’ tests for mass flow rates between 0.00653 and 0.0544 kg/s in an 8 mm ID tube. An annular flow model gave the best overall predictions of pressure drop. The homogeneous, and Beattle and Whalley (1982) models showed good agreement with the pressure drops measured for the slug and bubbly/slug flow conditions. The two‐phase multiplier deduced from the data appeared to follow the Martinelli‐Nelson trend but at lower values than for water.
