Date of Award

5-2018

Degree Type

Thesis

Degree Name

Master of Science in Aeronautical and Astronautical Engineering

Department

Aeronautics and Astronautics

Committee Chair

Steven F. Son

Committee Co-Chair

I. Emre Gunduz

Committee Member 1

Weinong Chen

Abstract

Aluminum-lithium (Al-Li) alloys have demonstrated a mechanism to improve composite propellant performance by reducing agglomerates through microexplosions. In addition, use of Al-Li significantly reduces hydrochloric acid production in ammonium perchlorate based propellants while also improving theoretical performance. Full combustion characterization (e.g., at various pressures) of the Al-Li based propellant has not been performed previously. Measurement of the aluminum-lithium composite propellant’s burning rate and quantification of agglomerate production at various pressures is presented. Agglomerate size of the aluminum-lithium appeared to be smaller at lower pressures than at higher pressures, likely due to increased microexplosions at low pressures. Additionally, at high pressures the aluminum-lithium did appear to produce larger agglomerates than the aluminum, but upon closer inspection it was observed that the majority of these large agglomerates were liquid metal that had splashed off of the melt layer rather than condensed phase oxide products. This biased the aluminum-lithium samples towards larger agglomerate sizes without clear evidence the larger agglomerates would not burn given greater residence time and distance from the surface. Results show a pressure exponent of 0.29 for a composite propellant using aluminum-lithium powder sieved to 25-40 μm and 0.39 for a propellant using aluminum-lithium powder as-received. The difference in pressure exponents for the two powder sizes could be attributed to the greater microexplosivity increasing the burning rate at low pressures

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