Towards Optimization of a Low Temperature Co-Fired Ceramic Catalyst Chamber for a Monopropellant Microthruster
Dr. Don Plumlee
The reduction in space vehicle size and mass presents the need to develop a proportionally smaller propulsion system for orbital station keeping. A Low Temperature Co-Fired Ceramic (LTCC) monopropellant micropropulsion device has been developed at BSU. The simple, robust design features a heterogeneous catalyst chamber used to decompose a rocket-grade hydrogen peroxide monopropellant, to produce thrust. Initial prototype testing indicates only partial peroxide decomposition requiring an in-depth analysis of the geometric layout of the devices to increase system efficiency. This study employs a control volume based methodology to analyze the performance of various catalyst chamber designs. This approach was chosen due to the inaccuracies and difficulties associated with modeling the exact kinetics of a two-phase, catalytic reaction at the micro-scale. A full factorial experiment was established to investigate the effects of several geometries, typical to LTCC fluidics, on the hydrogen peroxide decomposition percentage. Chamber geometries were chosen based on previous thruster designs as well as constraints related to LTCC fabrication capabilities. Test results will determine which chamber designs to investigate in future optimization efforts. Reaction completion percentage and chamber temperatures are measured at steady state operation and used to compare the chamber geometries studied. Initial testing validated the accuracy and repeatability of the test apparatus. Mechanical failure of devices occurred during the transient start-up phase of device testing as a result of localized thermal expansion. A functional prototype was achieved by decreasing propellant flowrate and cross-sectional area reducing the released thermal energy. This lowered thermal stresses within the LTCC to a controllable level. Test results suggest three-dimensional fluidic channels produce higher decomposition percentages than similar configurations limited to a single plane.