Visual study of low gravity cryogenic flow boiling

Flow visualization was used to view the boiling and other flow patterns of saturated liquid nitrogen upflow in a quartz tube test section. The experimental apparatus was subjected to low gravity conditions in aircraft parabolic flight experiments, and to normal gravity conditions during ground based tests. Data films from several days of tests were studied in detail. The various flow patterns seen during the ground tests were similar to those established by previous researchers. Differences between normal and low gravity boiling and other flow patterns were observed. Low gravity flow regimes for initial transition flows of dispersed droplets, wispy-annular flows ahead of the quench front, and the post quench liquid phase flows appeared to have characteristics different from those observed in previous ground based studies.

This thesis presents a discussion and catalogue of various 2 phase flow regimes encountered under transition to and from boiling processes. Further, the thesis presents a description of the differences in these regimes between the normal and low gravity environments, and makes recommendations for future experiments.