Influence of low-temperature chemistry on steady detonations with curvature losses

The influence of low temperature chemistry (LTC) on the locus of steady solutions predicted by a ZND model with curvature losses and detailed kinetics was assessed using undiluted / CO2-diluted stoichiometric DME-O2 mixtures. Results show (i) the existence of an additional critical point at large velocity deficits when the LTC submechanism is included in the reaction model, and (ii) a shift in the criticality from small to large velocity deficits as CO2-dilution is increased. Detailed thermo-chemical analyses revealed the importance of LTC in enabling an increased resistance to losses at large velocity deficits. LTC results in a temperature increase of ∼200 K at the beginning of the reaction zone that activates the intermediate and high temperature reactions, thereafter leading to the main heat release stage. Without a process that replenishes the OH radical pool at postshock temperatures below 1000 K the critical point at large velocity deficits ceases to exist.