| dc.description.abstract | Secondary dust explosions in coal mines or industrial settings are known to cause greater catastrophic hazards than the coupled primary explosions themselves. The shock waves produced during a primary explosion, which are initiated by inadvertent stimuli in an explosive atmosphere such as methane, lift surrounding coal particles from neighboring areas, and if added in an effort to create an inert mixture, limestone as well. This experimental study works with limestone dust, as its density is close to that of coal particles and its likely presence in the hazardous environment. The current study explored limestone moisture content to understand its effect on dust dispersion, which ultimately can influence the severity of a secondary explosion. A shock tube modified to evaluate dust dispersion provides the optical access to characterize the shock- wave / dust-layer interaction. Based on three shock Mach numbers, namely Ms = 1.1, 1.23, and 1.4, the trending data show an average increase of 10% in overall lifting heights and 20% in initial linear growth rates for the moisture-reduced, dried samples, as compared to undried samples stored in standard temperature and pressure (STP) conditions. Conceivably, the effective moisture reduction in the samples led to fewer agglomerations and/or reduced densities, influencing the ability of lift forces to act on the particles. The quantification of weight loss and weight differences between dried and undried samples was compared. The dust-layer rise height was measured with respect to time after the shock passage, where regardless of moisture content in the samples, initial dust growth rates increased with Mach number. Laminar and unstable regimes were also identified in the data samples, as seen in previous studies by the authors. | en |
