Ignition of thermally sensitive explosives between a contact surface and a shock

摘要

The dynamics of ignition between a contact surface and a shock wave is investigated using audone-step reaction model with Arrhenius kinetics. Both large activation energy asymptotics andudhigh-resolution finite activation energy numerical simulations are employed. Emphasis is on comparingudand contrasting the solutions with those of the ignition process between a piston and a shock,udconsidered previously. The large activation energy asymptotic solutions are found to be qualitativelyuddifferent from the piston driven shock case, in that thermal runaway first occurs ahead ofudthe contact surface, and both forward and backward moving reaction waves emerge. These wavesudtake the form of quasi-steady weak detonations that may later transition into strong detonationudwaves. For the finite activation energies considered in the numerical simulations, the results areudqualitatively different to the asymptotic predictions in that no backward weak detonation waveudforms, and there is only a weak dependence of the evolutionary events on the acoustic impedanceudof the contact surface. The above conclusions are relevant to gas phase equation of state models.udHowever, when a large polytropic index more representative of condensed phase explosives is used,udthe large activation energy asymptotic and finite activation energy numerical results are found toudbe in quantitative agreement.