SIMULATION OF THE GAS AND LIQUID BEHAVIOR IN A LIQUID HYDROGEN TANK WITH A STRAIGHT PIPE INJECTOR DURING PRESSURIZATION

In order to accurately predict the gas and liquid behavior during cryogenic propellant tank pressurization, a 2D axial symmetry volume-of-fluid (VOF) model is established by the computational fluid mechanics (CFD) method. The phase change model and the turbulence model are included in the pressurizing process and the relationship between physical properties and temperature is also considered. The simulation results for the hemisphere injector pressurizing have been compared with the experiment data of the National Aeronautics and Space Administration (NASA), and consistency between simulation and experiment has been achieved. The simulation results for the straight pipe injector pressurizing show that injecting the pressurizing gas toward the liquid surface causes large liquid hydrogen vaporizing at the liquid surface. The vaporizing mass is 0.067 kg, while the pressurizing gas mass consumption is only 0.038 kg. Most of the heat added by the pressurizing gas is used to increase liquid hydrogen and ullage temperature. The heat which was absorbed by the liquid used for the phase change occupies 10.41% of the total energy addition. The liquid convection between bulk liquid and surface liquid is suppressed during pressurization. Increasing the ullage temperature could improve the pressurizing velocity and save pressurizing gas mass consumption. The results are of benefit to the design of better propellant tank pressurizing modes for liquid launch vehicles.