Propellant Optimization for a Pulsed Solid Propellant Thruster System for Small Satellites

Abstract

CubeSats have historically been used mostly for education, technology demonstration, remote sensing, and amateur radio relay applications. Yet with increased maneuvering capability, they can become effective tools in on-orbit servicing and space debris removal. To make this a reality, CubeSats must be enabled to perform effective rendezvous and proximity operations with non-cooperative client objects, requiring a high-thrust propulsion system. As CubeSats are inherently constrained in their volume and mass, any propulsion system must feature a high specific impulse to minimize the propellant mass requirement. As CubeSats are commonly launched as secondary payload, the use of pressurized propellant tanks is typically ruled out due to concerns about the safety of the primary launch payload. One potential way of accomplishing this combination of high thrust, high specific impulse, and propellant safety is to base the propulsion system on electric on-demand combustion of solid propellant pellets. This thesis uses computational fluid dynamics to identify combinations of propellant chemistry, combustion chamber size, and ignition power resulting in an effective combination of thrust, specific impulse, and total impulse. The software package Flow-3D® was used to perform the simulations for this thesis. This thesis found that the combination of a 50/50 Nitroglycerin/Nitrocellulose propellant in a spherical combustion chamber with high power applied to the Nichrome wire ignitor produces the highest thrust, specific impulse, and total impulse out of all of the combinations.