Numerical Simulation of Detonation Wave Damping Using a Layer of Granular Material

Damping or quenching of detonation wave is of great importance for safety of
people, buildings, factories of chemical industries and equipment. In the
present paper a layer of granular material is used to achieve this purpose. The
main function of this layer is to absorb substantial part of both momentum and
energy of the wave. Eventually, the detonation wave is extinguished and the
pressure intensity is diminished. A model is given for drag force and heat
transfer exchange between gas and solid particles. The detonation wave is
initiated in a stoichiometric methane-air mixture at one end of a detonation
tube. A layer of granular material is attached to the other closed end. The
particles and the reactive mixture in the layer form a two-phase mixture that is
initially at rest and in thermodynamic equilibrium. The dynamics in the entire
domain following the collision of the propagating detonation front with the
gasllayer interface is investigated. The void fraction of the granular layer is
assumed constant (i.e. the particles velocity is zero). The chemical reaction is
assumed to be one-step reaction of Arrhenius type. The unsteady governing
equations in one-dimensional domair, are solved numerically. The effects of
solid particle diameters, specific heat and the void fraction variations on
detonation damping are found. The results show that considerable decay of
detonation occurs immediately at the gadlayer interface. The decay continues
along the layer until the wave is completely died out. The distance after which
the wave dies out was found to decrease with the decrease of solid particles
diameter and the void fraction and the increase of solid particles specific heat.
The reflected shock wave (retonation) from the gasllayer interface propagates
unsteadily backward and it is reflected from the closed end of the tube to strike
the gadlayer interface again. The transmitted part of the latter wave dies out
quickly inside the granular layer.