Propellant Management Devices

Communications Satellite

As a result of their demonstrated flight success and passive operation, surface tension Propellant Management Devices (PMDs) have become the propellant acquisition system of choice for earth-orbiting satellites, planetary spacecraft and, in some cases, launch vehicle upper stages. Many PMD functions in a low-gravity space environment cannot be tested on the ground. Consequently, design and qualification of a surface tension PMD requires a complete understanding of the mission requirements, a knowledge of surface tension effects, and a thorough knowledge of low-gravity fluid dynamics. The NASA Viking 75 Orbiter was the first long-life planetary spacecraft to use a surface tension PMD. The leader of the technical team that developed the Viking PMD in 1973-75 is a founder of Angeles Crest Engineering Inc (ACEI) and a staff member. The Viking PMD development started with concept generation and extended through flight qualification. Activities included the measurement of propellant surface tension and contact angle, drop tower model testing, neutral buoyancy model testing, prototype slosh testing, simulated fluid dynamic testing, performance modeling and simulation, and flight hardware design, fabrication and qualification.

ACEI has completed the conceptual design and performance analysis of numerous surface tension PMDs. PMD activities have included conceptual design, performance verification analyses, detailed design, fabrication and testing support. The verification analyses included establishing propellant configurations in a low-g environment, transient and steady state flow dynamics, reorientation dynamics, slosh dynamics and depletion analyses. Currently, more than thirty spacecraft are operating successfully in Earth orbit using these PMD designs.

ACEI developed a treatment process to enhance the wettability of Aluminum surfaces so that high performance surface tension PMD’s can be made of Aluminum. This process was developed under NASA sponsorship and was used for the PMD propellant tanks of the Global Precipitation Mission.

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