Influence of the chemical modeling on the quenching limits of gaseous detonation waves confined by an inert layer

Abstract

The effect of chemistry modeling on the flow structure and quenching limits of detonations propagating into reactive layers bounded by an inert gas is investigated numerically. Three different kinetic schemes of increasing complexity are used to model a stoichiometric H2–O2 mixture: single-step, three-step chain-branching and detailed chemistry. Results show that while the macroscopic characteristics of this type of detonations e.g. velocities, cell-size irregularity and leading shock dynamics, are similar among the models tested, their instantaneous structures are significantly different before and upon interaction with the inert layer when compared using a fixed height. When compared at their respective critical heights, hcrit, i.e. the reactive layer height at which successful detonation propagation is no longer possible, similarities in their structures become apparent. The numerically predicted critical heights increase as hcrit, Detailed ≪ hcrit, 3-Step < hcrit, 1-Step. Notably, hcrit, Detailed was found to be in agreement with experimentally reported values. The physical mechanisms present in detailed chemistry and neglected in simplified kinetics, anticipated to be responsible for the discrepancies obtained, are discussed in detail.