cfd analysis and thermodynamic modeling of gas behavior in liquid engine tanks

This study investigates the gas behavior within the propellant tanks of a pressurization system. a time-dependent thermodynamic model was developed to analyze the variations in gas properties, including pressure, temperature, and density, throughout the operation of the propulsion system. additionally, the behavior of the gas and liquid inside the tank during engine operation was numerically simulated using the fluent cfd package. the simulation employed the volume of fluid (vof) model and the standard k-ε turbulence model to resolve the turbulent two-phase flow in the tank. the numerical results for the gas phase obtained from the cfd simulation were compared with the thermodynamic model, demonstrating good agreement between the two approaches. the maximum discrepancy between the results was found to be less than 10%, for both pressure and temperature, and for both upper and lower tanks. while the thermodynamic model is effective for analyzing the average gas behavior over the system's operational duration, the cfd analysis provides detailed insights into the flow dynamics. this combination of approaches offers a comprehensive understanding of the system's performance.