Cryogenic Propellant Stratification in a Rotating and Reduced Gravity Environment

Abstract

Modeling the thermal stratification of cryogenic propellants within the upper stage of a launch vehicle is necessary for mission planning and successful execution. During orbital transfer the upper stage may coast for several hours during which time the propellants are heated by solar radiation. For orbital insertion at the conclusion of the coast the propellants must be within a narrowly defined range of temperature and pressure to ensure engine restart. This paper develops several simplified models of thermal stratification which include the low accelerations and thermal conditioning roll of the upper stage during the transfer coast. These models are used to assess the impact of thermal stratification within generic liquid hydrogen and oxygen tanks over a range of accelerations, spin rates, and incident solar heat fluxes for cylindrical tank geometries.