Thermodynamic Response of a Liquid Hydrogen Storage Tank for Aerospace Technology Under External Oscillation During Pre-Pressurization

Before launch, cryogenic propellant tanks experience a pre-pressurization stage during which their thermodynamic behavior is sensitive to operating conditions and external disturbances. For liquid hydrogen (LH2) storage tanks, small-amplitude oscillations may modify interfacial transport and phase change, thereby influencing pressure evolution and mass distribution. In this study, a computational fluid dynamics (CFD) model that accounts for gas–liquid interfacial phase change and environmental heat leakage is developed to investigate the thermodynamic response of an LH2 tank subjected to slight external oscillation during pre-pressurization. The effects of oscillation amplitude, inlet gas temperature, mass flow rate, and initial ullage gas fraction on temperature distribution, pressure development, and phase mass variation are analyzed. The results indicate that increasing the oscillation amplitude from 0.006 m to 0.014 m delays the pressurization time from 4.72 s to 5.04 s, while higher inlet temperatures (e.g., 330 K vs. 280 K) shorten the time to reach the target pressure but weaken interfacial condensation, resulting in a slower recovery of liquid hydrogen mass. Raising the inlet mass flow rate from 0.20 kg/s to 0.40 kg/s reduces the time to reach the preset pressure by approximately 56%, and larger initial ullage gas fractions (ullage height from 1 m to 6 m) significantly prolong the pressurization time and produce a wider high-temperature region. These quantitative results clarify the coupled oscillation-thermodynamic effects and can support optimization of LH2 tank operation during pre-pressurization.