Combustion of Gelled Propellants Containing Microsized and Nanosized Aluminum Particles

The combustion behaviors of gel fuels containing micro- and nanosized aluminum particles were investigated in a pressurized chamber under typical ramjet conditions. Condensed combustion products were sampled in the jet plume behind the exit nozzles with two different rapid-insertion probes. The chemical composition of the samples was determined, and the structure of the sampled combustion products was studied with microscopic techniques. The formation of large aggregates of aluminum was observed, which left the combustion chamber with limited oxidation. The formation of such aggregates could explain why the substitution of micro-Al with nano-Al did not lead to the expected increase in combustion efficiency.