Historical studies of particle interaction with air shocks were largely focused on dusty-gas shock tubes with uniform dilute powder mixtures contained in the driven section and subjected to a shock. The attenuation of the shock and displacement of the dust are key metrics, and results can generally be modeled numerically using single particle drag correlations. Dense particle concentrations are fundamentally different and are the subject of modern application in explosive dispersal of powders [1-2] in which the high-volume-fraction flow of particles dominates the post-detonation dispersal. Drag correlations for dense clouds of particles are available in the literature [3]. Experimental studies of denser particle layers and slugs have been conducted with initially stationary particles and a moving shock. Examples include shock interaction with layers of loose powders in a vertical shock tube [4], and shock interaction with a curtain of powder falling under gravity [5]. Denser slugs of lightly-compressed powders into wafers have been performed [6], however edge conditions in the vicinity of the particle volume are generally problematic. The foregoing examples all involve a planar shock interacting with a planar volume of particles with confining side boundaries. Real-world applications, including explosive dispersal of powders, often involve a high-speed moving particle cloud. Frost et al. [7] studied the interaction of a spherical blast wave with a metallized explosive flow field with micrometric reactive particles. In other applications, packets of larger dispersed particles may feature an attached bow shock when traveling supersonically. The resulting interaction with an oncoming shock, whether travelling or standing in air, includes shock-shock interaction, in addition to shock-particle interaction in the dense flow regime. The resulting trajectory and mitigating effects have yet to be scientifically quantified. Numerical modeling provides a framework for studying the essentially free-field interaction of a particle cloud during a shock encounter. This paper analyses the effects of particle size, particle material, cloud concentration, cloud shape, cloud velocity, and shock Mach number. The results are interpreted to assess the cloud deflection and momentum loss. Results show complex disintegration of the dense cloud and a range of deflection of the particle trajectory following breakup. Approved for public release under case number 96TW-2014-0188.
Refrences
[1] F. Zhang, D. L. Frost, P. A. Thibault and S. B. Murray, 2001 "Explosive dispersal of solid particles," Shock Waves, 10(6), pp. 431-443.
[2] C. M. Jenkins, R. C. Ripley, C.-Y. Wu, Y. Horie, K. Powers, and W. H. Wilson, 2013 Explosively Driven Particle Fields Imaged using a High Speed Framing Camera and Particle Image Velocimetry, Int. J. Multiphase Flow 51 pp. 73–86.
[3] N. Smirnov, "Combustion and detonation in multi-phase media: Initiation of detonation in dispersed-film systems behind a shockwave," Int. J. Heat and Mass Transfer, vol. 31, no. 4, pp. 779-793, 1988.
[4] X. Rogue, G. Rodriguez, J. F. Haas and R. Saurel, 1998 "Experimental and numerical investigation of the shock-induced fluidization of a particle bed," Shock Waves, 8(1), pp. 29-45.
[5] J. Wagner, S. Baresh, S. Kearney, W. Trott, J. Castaneda, B. Pruett and M. Baer, "Interaction of a planar shock with a dense field of particles," in Proc. 28th Int. Symp. Shock Waves, Manchester, 2011.
[6] M. Kellenberger, C. Johansen, G. Ciccarelli and F. Zhang, "Dense particle cloud dispersion by a shock wave," in Proc. 28th Int. Symp. Shock Waves, Manchester, 2011.
[7] D. L. Frost, S. Goroshin, R. Ripley and F. Zhang, Interaction of a Blast Wave with a Metalized Explosive Fireball, Proc. 14th Int. Det. Symp. (Coeur d’Alene, Idaho, USA, 2010)
