Numerical Simulation on Interface Evolution and Pressurization Behaviors in Cryogenic Propellant Tank on Orbit

Abstract

The interface distribution and self-pressurization phenomenon are the most important problems in the storage of cryogenic liquid on orbit, which are difficult to be predicted and assessed exactly due to the complex non-equilibrium thermal behavior. In this paper, one 3-D CFD model based on volume of fluid (VOF) method is established to investigate the interface evolution and self-pressurization process in the liquid oxygen (LOX) tank in microgravity environment with various heat loads and gravitational accelerations. The validity of the model is verified by both the present ground experiments and the drop tower experiments from literature. The impact of microgravity on the gas-liquid interface distribution in the cryogenic tank is analyzed. Different from the ground condition, the distribution behavior of the gas-liquid two-phase fluid in microgravity is that the liquid is covering the tank wall, and the ullage is staying at the top of the tank surrounded by the liquid. Then the pressurization rate of the tank with different gravitational accelerations is obtained. The tank pressure rise rate increases with the reducing of the gravity. The results are beneficial to the optimal design of the cryogenic propellant tank.