Date of Award
Master of Science
Travis R. Sippel
This work reports on organometallic composites containing nanoscale lithium-based hydride and aluminum fuels as solid propellant additives. Theoretical performance is evaluated for bimodal metal propellant formulations containing ‘nMx’ capped fuel additives (nanoMetallix LLC) and 32 ÃÂ¯ÃÂ¿ÃÂ½m aluminum. Replacing aluminum with nMx reduces adiabatic flame temperature, condensed-phase products, and hydrochloric acid, with some variants producing specific impulse similar to nanoaluminum-based propellants. Combustion behavior is investigated using high-speed video techniques, including flame emission, laser backlit configurations, and a two-camera ratiometric bandpass emission technique used to detect lithium. Agglomeration behavior of nMx particles at atmospheric pressure is similar to nAl, producing large aggregates that ignite quickly, increasing radiative heat feedback. Spectrally-filtered video identifies lithium vapor around nMx particles on and above the burning surface, suggesting lithium vapor is released close to the surface. Pressurized burning rate measurements indicate nMx-based propellant burning rates are up to ~14% higher than similar nAl-based propellants at and below 6.89 MPa. Above this pressure, nMx propellants exhibit plateau pressure dependence, likely an effect of different capping agents used. Static motor tests show specific impulse improvements over aluminized propellants. This work shows organically-capped nanoscale particles are a promising alternative to nano/micro-aluminum in composite solid propellant formulations.
Lawrence, Adam, "Experimental and theoretical investigation of organically-capped, nanoscale alkali metal hydride and aluminum particles as solid propellant additives" (2018). Graduate Theses and Dissertations. 16837.