Optical measurements of nano-aluminum combustion in a heterogeneous shock tube and in a flat flame burner

Metal additives are commonly used in combustion based devices such as high explosives and solid rocket motors. Of these, aluminum is the most common due to its availability, high energy density, and low toxicity; however, many aspects of nano-aluminum combustion are still not well understood. Depending upon the type of measurement, nano-aluminum burntimes can vary greatly and any reaction occurring at later burntimes is ignored. Also, much of the nano-aluminum work has been done using a heterogeneous shock tube, leaving hot post-combustion gas environments largely unstudied. The purpose of this study was to determine the burntime of nano-aluminum by measuring the heat release of the particles rather than relying on photon emission by the burning particles. By tracking the temperature of the ambient gases within the shock tube, specifically the OH radical chosen for its limited participation in the combustion event, a comparison can be made between the transient heat release of the particle and the luminosity curve giving a better understanding of nano-aluminum burntime. Also, similar burntime measurements were made in the hot ambient gases of a one dimensional flat flame burner. Three different particle sized were studied (50, 80, and 110 nm). The burntimes of each were measured using high speed CMOS imaging allowing for a comparison of burntimes in various types of environments. The results found OH could be used as an indicator of ambient temperature within the shock tube environment; however, the addition of nano-aluminum into the shock tube altered the signal of the absorption spectroscopy measurement. Also, the burntime results from the flat flame burner indicated that both single particles and larger agglomerations were present during testing and that the burntimes of single particles were consistent with burntimes observed in alternate environments