Mixing induced condensation inside propellant tanks

Onorbit storage and resupply of cryogenic fluids will be an increasingly important part of future space operations. The transfer of cryogens in a low gravity (low-g) environment requires that a receiver tank be filled with the vent closed to prevent loss of the incoming liquid. Mixing of the tank contents during fill is therefore required to induce condensation of the vapor and to provide control of the tank pressure. A subscale test program was conducted to investigate condensation rates produced by mixing the tank contents using a submerged liquid jet. The flowrate of the incoming liquid, and the angle at which the jet impacted the liquid surface were among the test parameters studied. The results showed that the injection angle had the most significant effect on the condensation rate. Condensation rates due to mixing were up to seven times greater than those measured without mixing. An analytical model was developed based on heat transfer due to a turbulent liquid jet. Agreement between the analytical model and the data was good for the tests of interest.