UVM Theses and Dissertations
Format:
Print
Author:
McDevitt, M. Ryan
Dept./Program:
Mechanical Engineering
Year:
2014
Degree:
Ph. D.
Abstract:
A focus area within the aerospace community has been in the development of miniaturized satellites in the 1 to 10 kg range. Often referred to as nanosats, these small satellites are envisioned to function cooperatively in clusters (formation flying) and enable new mission capabilities not possible with single satellites. Among the technological challenges associated with nanosats is the development of miniaturized propulsion systems (micro-thrusters) capable of producing very low thrust and impulse levels required to perform precise orbital station-keeping and positioning maneuvers. Monopropellant-based micropropulsion is an attractive scheme for micro-thruster applications since it offers a combination of relatively high energy density and reduced operational and design complexity.
The focus of this dissertation work has been targeted at the development of novel multiphase fuel injection and catalysis schemes for a MEMS-based hydrogen peroxide monopropellant micro-thruster design concept. Most notably, these schemes leverage flow phenomena unique to the micro-scale in order to address the challenging operational requirements. This work is primarily computational in nature, complemented by supporting experiments, and consists of two essential efforts.
The first is a discrete, multiphase flow fuel injection system that will allow for impulse-bits smaller than what is possible with existing technology. To support this work, a computational model has been developed to investigate the transient operation of the system and to perform parametric sensitivity studies to assess operational robustness and offer performance estimates. Results indicate a reduction in impulsebit size compared to traditional fuel injection systems over a range of operating conditions.
The second is the investigation of a discrete, multiphase method for enhancing mass diffusion in heterogeneous and homogeneous catalysis micro-scale reactors. Computational models are used to study the effect on decomposition of laminar and multiphase flow, and multiphase flow is found to significantly improve performance in both types of micro-reactors.
The focus of this dissertation work has been targeted at the development of novel multiphase fuel injection and catalysis schemes for a MEMS-based hydrogen peroxide monopropellant micro-thruster design concept. Most notably, these schemes leverage flow phenomena unique to the micro-scale in order to address the challenging operational requirements. This work is primarily computational in nature, complemented by supporting experiments, and consists of two essential efforts.
The first is a discrete, multiphase flow fuel injection system that will allow for impulse-bits smaller than what is possible with existing technology. To support this work, a computational model has been developed to investigate the transient operation of the system and to perform parametric sensitivity studies to assess operational robustness and offer performance estimates. Results indicate a reduction in impulsebit size compared to traditional fuel injection systems over a range of operating conditions.
The second is the investigation of a discrete, multiphase method for enhancing mass diffusion in heterogeneous and homogeneous catalysis micro-scale reactors. Computational models are used to study the effect on decomposition of laminar and multiphase flow, and multiphase flow is found to significantly improve performance in both types of micro-reactors.