Numerical optimization of a liquid propellant settling scenario

Computational fluid dynamic modeling was utilized to numerically optimize liquid propellant settling in a liquid hydrogen tank based on the Weber number. Propellant settling is the process by which thrust is provided to move the propellant to the bottom of the tank. Constant accelerations were used to simulate four different Weber numbers. Propellant settling times and the corresponding required change in velocity (DeltaV) were calculated from the simulations for each Weber number, with the goal of optimizing the propellant settling process by minimizing DeltaV. Because the lower Weber numbers cannot be achieved in a flight-like scenario, a pulsed acceleration strategy was used to create a time averaged Weber number for comparison. The liquid propellant can be settled using the pulsing strategy, and a similar settling time can be achieved. The model was validated against a drop tower test conducted at the National Aeronautics and Space Administration's Lewis Research Center.