Similarity analysis for reorientation and self-pressurization of cryogenic fluids in on-orbit propellant tanks

Abstract

Cryogenic propellants are identified as one of the most promising technologies due to their advantages in specific impulses. However, there still exist gaps in the available knowledge of microgravity cryogenic fluid management, particularly on a large scale. In this study, scaling laws for the interface reorientation and self-pressurization conditions are proposed and validated. Accurate scaling for stationary self-pressurization conditions was achieved by adopting $Fo$ and $Bo$ as similarity criteria. For interface reorientation conditions, the pressure is influenced mainly by the rapid condensation on the interface. The time-factor is proposed to decouple the evolution of the interface and the characteristic length. A new scaling law, $t\sim L^{1.65}$, is proposed to improve the interface similarity between the subscale and the prototype models. The new scaling law significantly improved the pressure prediction accuracy in the scaled models, with a maximum pressure deviation of less than 5%. The scaling methods for the on-orbit cryogenic propellant fluids were systematically proposed and examined by drop tower and ground-based experiments. The results provide a theoretical basis for further scaling experimental and numerical studies of on-orbit cryogenic storage.