Convective combustion modeling applied to deflagration-to-detonation transition of HMX

A two-phase reactive flow analysis has been applied to predict the possibility of deflagration-to-detonation transition (DDT) in packed beds of granulated HMX. The unsteady fluid mechanics during the ignition and flame-spreading sequence through porous beds provides a rapid pressure buildup, suggesting the formation of a shock wave. A specific criterion of critical P²τ was interpreted as satisfying requirements that would lead to the onset of detonation. A parametric study of granulated HMX has shown that important variations of the runup length to detonation exist for parameters that relate directly to the explosive mass and energy generation rates. These sensitive parameters are particle diameter, porosity, burn rate, and chemical energy of the explosive. Smaller effects due to drag, heat transfer correlations, ignition criterion, and numerical smoothing techniques do not seriously affect runup length magnitudes and are essentially uncoupled from the effects of the sensitive explosive parameters in establishing trends.