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Two immiscible fluids converging at microchannel cross-junction results in the formation of periodic, dispersed microslugs. This microslug formation phenomenon has been proposed as the basis for a fuel injection system in a novel, discrete monopropellant microthruster design for use in next-generation nanosatellites. Previous experimental work has demonstrated the ability to repeatably generate fuel slugs with characteristics commensurate with the intended application. In this work, numerical modeling and simulation are used to further study this problem, and identify the sensitivity of the slug characteristics to key material properties including surface tension, contact angle and fuel viscosity. These concerns are of practical concern for this application due to the potential for thermal variations and/or fluid contamination during typical operation. For each of these properties, regions exist where the slug characteristics are essentially insensitive to property variations. Future microthruster system designs should target and incorporate these stable flow regions in their baseline operating conditions to maximize robustness of operation.

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This study focused on the development of a chemical micropropulsion system suitable for primary propulsion and/or attitude control for a nanosatellite. Due to the limitations and expense of current micropropulsion technologies, few nanosatellites with propulsion have been launched to date; however, the availability of such a propulsion system would allow for new nanosatellite mission concepts, such as deep space exploration, maneuvering in low gravity environments and formation flying. This work describes the design of “dual mode” monopropellant/bipropellant microthruster prototype that employs a novel homogeneous catalysis scheme. Results from prototype testing are reported that validate the concept. The micropropulsion system is designed to be fabricated using a combination of additively-manufactured and commercial off the shelf (COTS) parts along with non-toxic fuels, thus making it a low-cost and environmentally-friendly option for future nanosatellite missions.