Scaling and Modeling of Propellant Sloshing and Zero Gravity Equilibrium for the Orion Service Module Propellant Tanks

Abstract

A scaled model of the downstream Orion service module propellant tank was constructed to assess the propellant dynamics under reduced and zero-gravity conditions. Flight and ground data from the experiment is currently being used to validate computational models of propellant dynamics in Orion-class propellant tanks. The high fidelity model includes the internal structures of the propellant management device (PMD) and the mass-gauging probe. The scaling of these structures in parallel with the scaling of the simulated propellant, Monomethalhydrazene (MMH), comprised the primary scientific focus during experimental design. In particular, this thesis addresses the geometric scal- ing of the Orion SM tank and the scaling of the Orion propellant properties through a scaling relation of the Bond number. A clear understanding of the fluid dynamics within the tank is necessary to ensure proper control of the spacecraft’s flight and to maintain safe operation of this and future service modules. Qualitative differences between exper- imental and CFD data are understood in terms of fluid dynamical scaling of inertial and capillary effects in the scaled system. Understanding slosh dynamics in partially-filled propellant tanks is essential to assessing spacecraft stability.