Development of an Analytical Model: Tank Pressure Control Experiment

The “Reduced-Fill Tank Pressure Control Experiment (TPCE/RF)” is a space experiment developed to meet the need for a critical aspect of cryogenic fluid management technology: “control of storage tank pressures in the absence of gravity by forced-convection mixing”. The experiment used Freon-113, at near saturation conditions and a constant 40% fill level, to simulate the fluid dynamics and thermodynamics of cryogenic fluids in space applications. The objectives of TPCE/RF were: Characterize the fluid dynamics of an axial jet-induced mixing in low gravity. Evaluate the validity of empirical mixing models, and provide data for use in developing and validating computational fluid dynamics model of mixing processes. TPCE/RF accomplished all of its objectives in flight on the Space Shuttle flight in May 1996. The flow patterns observed generally agreed with a prior correlation derived from drop tower tests. Several existing mixing correlations were found to provide reasonable performance predictions. Low-energy mixing jets, dissipating on the order of 1% of the kinetic energy of previous mixer designs, were found to be effective and reliable at reducing thermal non-uniformities, promoting heat and mass active mixing, whether continuous or periodic, offers increased reliability and predictability in space cryogenic systems and can be accomplished with no significant boiloff penalty caused by kinetic energy dissipation.