Pressurization performance and temperature stratification in cryogenic final stage propellant tank

One CFD model is established to investigate the pressurization performance and thermal stratification in the final stage cryogenic liquid oxygen (LOX) tank, which is subjected to aerodynamic heat and space radiations during launch. Iterative calculation with variable physical properties in each time step, both aerodynamic heat and space radiation have been considered by compiling one UDF and implanting it into the CFD model. It turns out that aerodynamic heat has caused large influence on tank pressurization performance, while the effect of space radiation on tank pressurization is not obviously reflected. Influenced by the injection gas, tank pressure fluctuates between the minimum and the maximum pressure limit and the ullage mass decreases due to condensation during the active-pressurization. Meanwhile, the basic parallel advance trend of temperature distribution is roughly formed. During the pressurized discharge, tank pressure experiences a sharp decline at first, then decreases linearly, finally reduces with a larger rate. The liquid temperature increases gradually to the direction of advance as liquid height declines. Moreover, the residual liquid temperature increases obviously. With the heat continuous transferring from the ullage to the liquid, the ullage is under condensation during the whole process.