Proton radiography of explosively dispersed metal particles with varying volume fraction and varying carrier phase

A series of experiments were performed to provide validation data for explosively driven multiphase flows at moderate-to-high volume fractions. A 13 × 6 mm cylindrical packet of 115- μ m steel particles was dispersed explosively. In contrast to shock tube studies, the particles were subjected to a high-Mach-number shock, in the presence of an ambient fluid, and a contact interface between the ambient and the explosive products. The first five experiments lowered the global volume fraction by replacing portions of the particle bed with hollow glass microspheres, dispersing the particles into vacuum. Three global fractions were investigated: 60%, 40%, and 20%. The next five experiments did not lower the volume fraction but instead varied the ambient fluid. Three ambient fluids were investigated: air, xenon, and SF 6 . To penetrate the optically opaque explosive products present and track the dispersed particle cloud, proton radiography was performed. The high-volume-fraction cases exhibit a piston-like motion for all ambient conditions, with an increasingly stochastic motion present for the lower volume fractions. Particle fronts extracted from the transmission radiographs exhibit almost constant velocity. Furthermore, centerline particle fronts for the high-volume-fraction cases, with both vacuum and varying ambient gas conditions, were almost the same, suggesting the primary impulse to particle bed motion arises from the contact interface between the ambient and the detonation products. Lower volume fractions were accelerated to higher velocities, behaving as though they were a single object of decreased density being acted on by a force of constant magnitude.