Online

Harvey, William J.

Mechanical Engineering

2023

M.S.

With advances in space technology, the use of satellites in commercial and academic settings have progressed immensely. The increase in satellite usage has created a need for on-board propulsion systems that provide in-space mobility. Satellites often require maneuvers such as collision avoidance, de-orbiting, and changing orbital positions. These maneuvers help to reduce space clutter but also enable longer and more capable missions. However, chemical propulsion systems present a number of challenges, particularly during launch. Satellites require the use of large rockets to deliver them in space and the addition of a propulsion system means that the rocket will be carrying equipment loaded with high pressure vessels. The On-Demand Pressure System (ODPS) removes the need for a pressurized tank on launch, reducing the risk and cost to send a satellite to space. Instead, a solid powder propellant known as Azodicarbonamide, commonly referred to as Azo, is thermally decomposed into a gas when pressure is needed. The Azo decomposition is extremely exothermic, resulting in a blast wave that shocks the system with a high temperature and pressure gas. The reaction produces gas but also solid residue that can clog plumbing in the ODPS. This research aims to find methods to reduce the energy of the resulting blast wave as well as characterize the steady state pressure and residue buildup in the ODPS. This research utilizes an experimental ODPS system comprised of high pressure vessels and transducers to study the blast wave. The first set of experimentation focuses on the application of vacuum suppression to reduce blast wave energy. A secondary objective for this is to characterize the steady state pressure of the system for varying masses of Azo and to quantify the weight and location of solid by-product from the reaction. The results of the vacuum suppression tests found that this method was able to reduce the incident pressure of the blast by 33% on average and slow the blast speed from supersonic to subsonic. The steady state pressure and total mass of residue were found to have strong linear relationships for a given Azo loaded mass. The second set of experimentation studied the effect of heat aging on the reaction kinetics. Heat aging was found to increase the incident pressure when aged up to three hours, but dramatically decreased the incident pressure for heat age times of four hours and longer. However, decreases in steady state pressure are also observed for heat age times of four hours and longer. By developing incident pressure mitigation strategies and characterizing critical parameters of the ODPS, this research provides valuable insights for optimizing geometry and selecting appropriate components for more effective On-Demand Pressure Systems.