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International Journal of Energetic Materials and Chemical Propulsion
ESCI SJR: 0.149 SNIP: 0.16 CiteScore™: 0.29

ISSN Imprimir: 2150-766X
ISSN En Línea: 2150-7678

International Journal of Energetic Materials and Chemical Propulsion

DOI: 10.1615/IntJEnergeticMaterialsChemProp.v3.i1-6.330
pages 313-326

CHARACTERIZATION AND DIAGNOSTICS OF SINGLE PARTICLES OXIDIZED IN AN ELECTRODYNAMIC CHAMBER

Yony Weiss
Department of Mechanical Engineering, Ben-Gurion University of the Negev, Israel
Ezra Bar-Ziv
Department of Mechanical Engineering, Ben-Gurion University of Negev, P.O. Box 653, Beer-Sheva, Israel

SINOPSIS

The aims of this study are (1) to present the further development of some of the characterization methods used with the electrodynamic chamber (EDC) for high-temperature studies of single particles and (2) to present in a qualitative manner new results on char oxidation under kinetically controlled conditions. The following methods were either developed or improved: (1) shadowgraphy for size and shape measurements; (2) two-dimensional Mie scattering for sizing and determining optical properties; (3) drag force measurements (by forced convection) for determination of density; and (4) optical pyrometry using wide-band detectors in the visible and infrared regions for temperature determination. In this study, synthetic char particles, spherically shaped (Spherocarb - of very high porosity), as well as spherical polystyrene particles (with no porosity) were oxidized in atmospheric air. The particles were suspended in the center of the EDC and heated by a CO2 laser beam. The particles were characterized prior to reaction by the above methods. Mass and size changes as well as particle temperature were measured as functions of time during the oxidation process. The particles were consumed in the following manner: First, they were consumed uniformly, following previous shrinkage observations. At about 60% conversion, non-uniform shrinkage was observed. At 70% conversion, a clear cut on the top of the particle was monitored. At 80% conversion, preferential consumption from the other side of the particle was established, showing a clear disk configuration. At 95% conversion a hole in the center of the disk was developed. Reasons for preferential consumption might be (1) non-uniform radiation of the particle (particle is irradiarted from bottom only) that generated a temperature differential at the particle, or (2) non-uniform evolution of the pore structure even for uniformly heated particles.