Numerical Study On The Attenuation Effect On The Blast Wave Of Encircling A High Explosive With Granular Media

This study explored the practicality of a two-phase flow model for granular media in elucidating the attenuation mechanism of the blast wave. To validate the model, the numerical data were compared with the results of the previous experiments in terms of the interaction between the planar shock wave and particle layer, dispersal of steel particles saturated with a liquid explosive after the detonation of the explosive, and attenuation effect of the particle layer on the blast wave. Results of the validation confirmed good agreement and consistency between both data. Next, the attenuation effect on the blast wave created by a spherical pentolite by encircling the high explosive with a particle layer of sand was investigated, where the main parameter for comparison was the particle layer thickness. Here, a thicker particle layer further attenuated the blast wave, whereas a thinner one was accelerated to a velocity exceeding the sound speed of air, which generates a secondary shock wave ahead of the particle layer and behind the incident shock wave. When the secondary shock wave was coupled with the incident shock wave, the blast wave strength was locally recovered. To quantitatively comprehend the attenuation mechanism of the particle layer on the blast wave, the total energy transfer between the particle layer and air was computed. Results revealed a strong correlation between the blast wave strength and the amount of energy transferred between the particle layer and air and to the flow structures generated by the particle motion.