Removal Rates of Explosive Particles From a Surface by Impingement of a Gas Jet

Abstract

The rate of particle removal from a surface by air jet impingement has been evaluated for 3 different types of trace explosives. Samples of research development explosive (cyclotrimethylenetrinitramine), trinitrotoluene, and C-4 were each transferred to glass surfaces and then subjected to a short burst of air from a jet with varying diameter, standoff distance, and backpressure to achieve a range of shear stresses at the surface. TNT was observed to be easiest to remove, while C-4 required the greatest shear force to resuspend. An analytical model has been developed to predict removal of spherical particles as a function of particle diameter and nondimensionalized downstream distance from a gas jet. This model was fitted to experimental data from the removal of ceramic microspheres of various sizes. The removal rate of these ceramic microspheres was observed to be much greater than that of the 3 types of explosive particles, despite the particles’ similar sizes. Copyright 2012 American Association for Aerosol Research