In view of the tank pressurization process of a certain liquid rocket during outflow

a two-dimensional numerical simulation method was adopted to study the law of temperature distribution in the ullage gas and in the tank wall. In this model

the low-Re k-ε model was selected to calculate the coupled heat transfer between fluid and tank wall

and a user-defined function (UDF) for phase transition was compiled and embedded into Fluent so as to research the effect of heat and mass transfer at the liquid surface. Certain experimental data in reference were selected to verify the results of this model on the same condition. The comparison results show that this two-dimensional model can forecast axial temperature distribution in ullage gas and in tank wall correctly. In addition

the computation results show that the effect of the direction and the area of pressurized gas injector on the axial temperature distribution in the ullage gas and in the tank wall is weak

but the temperature field nearby gas inlet is little affected by them. When pressurized gas is injected downstream into the tank ullage

the gas temperature nearby tank top is lower

which may be favorable to the normal operation of relief value. When pressurized gas is injected into the tank ullage horizontally

the bigger diameter of the injector means larger high-temperature region nearby the tank top.