Aluminium dust-air detonation at elevated pressures

Understanding the detonability of aluminium particles suspended in air at elevated pressures is important in problems associated with industrial safety, stagnation flow, or shocked flow conditions. While micrometric aluminium dust-air detonation at atmospheric conditions is feasible in large tubes using a strong initiation source [1, 2, 3, 4], the detonation properties and structure at elevated pressures have not been carefully investigated. For organic dust with a high volatile content, the detonation sensitivity is increased with increasing initial pressure, approximately following the scaling rule of gaseous detonations in which the detonation cell size is inversely proportional to initial pressure [4, 5]. However, aluminium particles possess an oxide layer that has a high melting temperature, thus increasing the difficulty of detonation initiation and the understanding of the detonation mechanism. The aim of the present paper is to study the influence of elevated initial pressures on the detonation properties and structure in aluminium dust-air mixtures. To understand the scaling effect of particle size, experiments were carried out for a nanometric and a micrometric aluminium particle size at various particle concentrations.