Simulation Study on Thermal Stratification inside Cryogenic Tank under High Heat Flux Condition of Vehicle Launching

To reveal the temperature field distributions of the bare-wall cryogenic propellant tank during vehicle launching, a coupling simulation model, including fluid region and solid wall region, was established to realize the continuous prediction of ground pre-pressurization, launching aerodynamic heating and pressurized discharge processes. The thermal stratification and pressurization performance inside a bare-wall tank and a foamed wall tank were compared. The simulation results show that the pressurization effect in the pre-pressurization stage was closely related to the thermodynamic state in the ullage region of the tank. Aerodynamic heating in the lift-off process of the bare-wall tank could produce strong natural convection and thermal stratification, which further affected the temperature quality of liquid oxygen. The maximum temperature of liquid oxygen in the tank might exceed 93 K. The effect of aerothermal heating on the temperature of cryogenic propellant in the tank could be significantly reduced by using a foam insulation layer. Generally, the present research could provide guidance for the design of thermal insulation scheme for rocket cryogenic tank in the future.