Date of Award:

12-2019

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Mechanical and Aerospace Engineering

Committee

Stephen A. Whitmore

Committee

David Geller

Committee

Geordie Richards

Abstract

A hybrid thruster system utilizes propellants in two different stages, traditionally a solid fuel and a gaseous or liquid oxidizer. Recently hybrid thrusters have become a popular topic of research due to the high demand of a ”green” replacement for hydrazine. Not only are hybrid thruster systems typically much safer than hydrazine, but they are also a low-cost system with a high reliability in performance. The Propulsion Research Laboratory (PRL) at Utah State University (USU) has developed a hybrid thruster system using 3-D printed acrylonitrile butadiene styrene (ABS) as the fuel and gaseous oxygen (GOX) as the oxidizer. This system has been spaceflight flown and tested in a hard vacuum environment with success. However, GOX has a low density and must be stored at high pressures to be considered viable. This thesis investigates the use of N2O/O2 mixtures, ”Nytrox”, and more commonly known as ”laughing gas”, as a higher density replacement oxidizer for GOX. Ina manner directly analogous to the creation of soda-water using dissolved carbon dioxide, Nytrox is created by bubbling gaseous oxygen under high pressure into nitrous oxide until the solution reaches saturation level. Oxygen in the mixture ullage dilutes the nitrous oxide vapor, and increases the required decomposition activation energy of the fluid by several orders of magnitude. Data from tests using each oxidizer are analyzed and presented for performance comparisons. Comparisons include, ignition reliability, ignition energy, thrust coefficient, characteristic velocity, specific impulse, and regression rate. Nytrox is shown to work effectively as a “drop in” replacement for gaseous oxygen, exhibiting slightly reduced specific impulse and regression rate, but with the trade of a significantly higher volumetric efficiency.

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