Proposed is a knowledge gathering payload to generate data, from a unique and tailored geometry with some zero-g flight heritage, to drive improvements in simulation of non-linear contact line…

This is a $226,149.59 federal grant awarded by the National Aeronautics and Space Administration (NASA) to Purdue University, a prominent public research university, to conduct a knowledge gathering payload experiment focused on improving simulations of non-linear contact line motion and low-gravity propellant slosh motion. The objective is to generate data from a tailored testing geometry with some prior zero-gravity flight heritage, in order to better model and predict this common spacecraft phenomenon during events like orbit raising burns or docking maneuvers. This work is intended to help address the lack of existing data and models for this low-gravity fluid dynamics issue, which has implications for smaller satellite designs. The grant has a performance period through June 30, 2024 and does not utilize any set-aside designations.

Proposed is a knowledge gathering payload to generate data, from a unique and tailored geometry with some zero-g flight heritage, to drive improvements in simulation of non-linear contact line motion (or contact angle) on natural frequencies for the capillarydominated phenomenon of low-g propellant slosh motion. Non-linear contact line motion (or equivalently, hysteresis in dynamics contact angle) had been known since the 1960S to be able to have a large effect, such as a factor of six, on the fundamental natural frequency, and presumably on harmonics too. When acceleration exists for the spacecraft, such as during an orbit-raising burn or a trajectory acceleration or correction burn, the acceleration-induced pressure gradient generally dominates over capillary effects and slosh is nearly as simple as one-g slosh on earth. Two considerations, one old and one new, create a need for gathering data on the low-g response, such as propellant (or coolant, water, or other liquid in use in a spacecraft) settling after a maneuver or docking event or motion of a robotic servicing vehicle, etc: first, little data exists for this common event in spaceflight and thus few models for computation and design exist, and second, the new trend towards smaller satellites reduces uncertainty from scaling up data from these small fluids payloads to true scale (and no large fluids experiment has been to or is headed to ISS.) the proposed payload will fly on a single blue origin sub-orbital flight in their double-height payload locker and will fit their standard mass, size, control, power, and data acquisition constraints. The novel design for the testing geometry creates two-dimensional mean flow and contact line motion in a three-dimensional container such that the knowledge gathered will be of use for subsequent technology developers to advance most efficiently the development of practical data-based models for the major non-linearities of contact line motion.