Blast enhancement from metalized explosives

Abstract

Experiments are carried out to determine the effects of particle size and mass loading on the free-field blast wave from spherical, constant volume metalized explosive charges. The charges are comprised of gelled nitromethane with uniformly embedded aluminum, magnesium, or glass particles. Particle sizes are varied over an order of magnitude with particle mass fractions up to 50%. Peak blast overpressures are directly measured within the fireball with piezoelectric pressure gauges and outside the fireball are inferred by tracking the velocity of the blast wave and using the Rankine–Hugoniot relation. With the addition of inert particles, the peak blast overpressure is initially mitigated, but then recovers in the far field. For charges with reactive particles, the particles react promptly with oxidizers in the detonation products and release energy as early as within the first few hundred microseconds in all cases. The particle energy release enhances the peak blast overpressures in the far field by up to twice the values for a constant volume charge of the baseline homogenous explosive. By plotting the peak blast overpressure decay as a function of energy-scaled distance, it is inferred that at least half of the particle energy release contributes to the blast overpressure in the far field of higher mass loadings, and nearly all of the particle energy for a particle mass fraction of 10%. For aluminum, the blast augmentation is not a systematic function of particle size. This observation implies that conventional models for particle combustion that depend on particle surface area are not appropriate for describing the rapid aluminum reaction that occurs in the extreme conditions within the detonation products, which influences the blast wave propagation.

Turbulent, Rossby, rogue and explosive nonlinear waves in plasma at Titan’ s ionosphere

“…This high-pressure zone then expands outward as a shock wave, with a sharp increase in pressure and temperature. The behavior of an explosive wave depends on a number of factors, including the energy and duration of the initial event, the density and composition of the surrounding medium, and the distance from the source of the explosion (Almustafa and Nehd 2023;Pontalier et al 2021).…”

Shock ignition of aluminium particle clouds in the low-temperature regime

“…According to Tanguay et al [4], the addition of aluminium or magnesium particles in a high explosive will lead to an increase in energy release of 5-6 times more than the bare high explosive. The results are observed in the far field [5] as an increase in the blast peak Communicated by D. Frost. overpressure. This is due to the fact that aluminium has a high density and a high heat of combustion.…”

Time of arrival as a diagnostic for far-field high explosive blast waves

“…The optically evaluated pressures from each of these studies demonstrated reasonable levels of agreement with gauge recordings between 0.8 and 5.2 m/kg 1/3 . Pontalier et al (2021) undertook a comprehensive optical analysis of shock wave propagation from metalized explosives across the intermediate scaled distance range (1.0-3.5 m/kg 1/3 ), measuring both fireball and fragment expansion rates. The results of which presented reasonably high variability of both arrival time and peak pressure when comparing nominally identical tests.…”