On the liquid layer formation and thermodynamic behavior of liquid oxygen during interface reorientation: A combined drop tower experiment and simulation study

The interfacial movement and thermodynamic behavior of the cryogenic propellant during the reorientation process is crucial for their on-orbit storage and management systems. However, the low surface tension and viscosity of the cryogenic fluid, together with its low saturation temperature, results in a complex evolution of the interface movement under step changes in gravity. In this work, a cryogenic drop tower apparatus was developed to examine the evolution of interface position, temperature, and pressure. The numerical simulations were also performed to analyze the related phenomenon based on the open-source OpenFoam platform. The results show that the interface center undergoes damped oscillations spanning three complete cycles within 2.5 s. Furthermore, a thin liquid layer forms during the first recession of the contact line, with its motion decoupled from that of the oscillating liquid bulk. The formation of the liquid layer results from significant stress torque at the evaporation–condensation transition, which thins its lower edge. During the secondary rise of the contact line, evaporation dominates the interfacial phase change due to prolonged heat exchange with the wall, preventing liquid-layer formation during the subsequent retreat. Regarding thermodynamic behavior, gas temperature remains unaffected by interface fluctuations at distances exceeding the maximum height of the contact line. The gas temperature continues to rise at a rate of 0.19 K/s beyond 34.8 mm due to heat conduction through the wall. The maximum pressurization rate induced by liquid layer reaches 3227 Pa/s. The present study could provide guidance for the design of on-orbit management for cryogenic propellants.