Study on the Jet Formation During Dispersal of Solid Particles by Shock and Blast Waves

During the last decade, investigations have been achieved to determine the physical mechanism which governs particle jet formation induced by the dispersion of a granular medium exposed to an impulsive pressure load, i.e., by a shock or a blast wave. This kind of such physical mechanism is observed during explosions or in nature as volcanic eruptions [1]. The formation of particle jets is also observed when a solid projectile impacts a particle layer [2]. Previous experiments have been conducted so far in three-dimensional spherical configurations using explosives surrounded by a granular layer [3–7]. In these experiments, the particle jet formation was obtained and clearly observed. The attempt was to correlate the particle jet distribution to the initial parameters like the particle diameter and density, the particle layer thickness and the strength of the incident shock wave in order to understand the breaking mode of a solid particle cluster. Even if it has been shown that the formation of particle jets depends both on the particle material properties and the ratio between the particle layer and the explosive mass [3], it was quite difficult to accurately relate the jet distribution with the initial conditions. More recently, cylindrical experiments were performed by Frost et al. [8] where it was easier to observe the particle jet formation. In spite of these studies, the selection mechanism is still not understood. The present experimental study was conducted in quasi two-dimensional geometry in order to ensure accurate characterization of the phenomenon. We present the concept of the two-dimensional experiments carried out. Parameters such as material density, strength of the incident shock wave, and the initial geometry of particle rings can be changed in order to find out what parameters can control the breaking mode of the particle clusters [9].