MEASUREMENTS OF JET-INDUCED PRESSURE DECAY IN A THERMALLY STRATIFIED TANK

Forced mixing may be required for controlling pressure during in-space storage and transfer of cryogenic propellants and life support fluids . To provide applicable data on jet-induced mixing, a 1-g experiment w as conducted in which an axial jet mixer promoted condensation of the ullage and lowered the pressure in a subscale cylindrical tank partial ly filled with thermally stratified Freon 11. The experiment objective s were to 1) correlate pressure reduction times with experiment parame ters, 2) compare the pressure reduction times to mixing times determin ed by previous investigations using acid-base neutralization and dye d ispersion, and 3) determine the transient condensation and heat transf er rates at the liquid surface as a function of jet parameters. Pressu re reduction times were correlated with the rate of jet momentum addit ion to the bulk fluid. Dimensionless pressure reduction times agreed w ith comparable acid-base neutralization data, but not with dye dispers ion data. The variation of interface heat transfer coefficient with ch anges in jet Reynolds number was consistent with an existing correlati on based on measurements of steady-state rates of mixing-induced conde nsation of steam.