Niemiec, Nicholas Anthony (2018-08). Advanced Laser Diagnostics for Characterization of Particle Flow Field and Chemical Species During Energetic Material Reactions. Master's Thesis.
Thesis
Inhaling air-borne metal particles is known to cause adverse health effects such as cancer, pulmonary heart disease, and asthma, to name a few. Metal particles can be released to air from various additives often used to produce desired combustion characteristics of propellants, pyrotechnics and explosives. The focus of the present study is to characterize the release of metals during energetic reaction of defense-related explosive compounds. Evaluation of health effects and deriving proper mitigation strategies require in-situ diagnostic methods of measuring the concentration of metal particles within the flame zone of an explosive material reaction. The experiments described here characterize those metal particles, as well as their flow pattern, in the vicinity of the flame zone. Propellant strands are used to create a controlled flame zone for study, with each strand containing varying amounts of concentration of different metals of interest. High-speed digital in-line holography (DIH) is used to quantify particle size, particle velocity, three-dimensional location within the flame zone, and the density of particles within the region of interest. Under current experimental conditions, the particles imaged were found to be 100-200 microns, with an average velocity of 3 m/s. As the particles ejected spread out in different directions, the spatial location closest to the strand contains the highest density of particles. The chemical composition, specifically the type of metal concentration of the ejected particles is observed through a simultaneous laser-induced breakdown spectroscopy (LIBS) experimental system. The spectrally resolved emission following a localized plasma generated using an intense nanosecond-duration LIBS laser pulse reveals specific metal type and relative concentration. To the best of our knowledge, the present work demonstrates simultaneous particle flow-field characterization and metal speciation using combined DIH and LIBS techniques, in a gas-phase reacting flow field.
