Hump and mass-transfer characteristics of dissolved oxygen induced by gaseous cavitation in a space micropump

Abstract

Fuel transportation in on-orbit refueling and circulation systems used in space involves dynamic transitions in the gas–liquid behaviors. Based on our verified innovative computational model of dynamic dissolution and evolution, the interesting “hump characteristics” of the dissolved oxygen concentration (DOC) were discussed, and the space-spatial evolution of gas–liquid mass transfer were compared. The hump phenomenon is related to the evolution of gas in the suction chamber. The processes undergone by the released gas, including the local evolution, evolution expansion, and global evolution, which were observed for the first time in rotating machinery owing to the pressure fluctuations caused by the impeller. Limited by the mass-transfer rate, the pressure increase in the impeller was significantly greater than the increase in the DOC, and thus there was no gas evolution inside the impeller. With an increase in the initial DOC, the near-zero mass-transfer rate band split into two and moved downstream of the blade, indicating a dynamic balance between the dissolution and evolution. Moreover, the flow separation and vortices near the clearance widened the band and decreased the dissolution rate. The current research provides an in-depth understanding of the dynamic changes in the gas–liquid behavior of on-orbit refueling systems.