Unsteady propagation of detonation with multi-stage heat release

This work numerically studies the propagation characteristics of detonation waves with multi-stage heat releases (MSHR) for stoichiometric dimethyl ether/oxygen (DME/O₂) mixtures with carbon dioxide (CO₂) addition. Results show that detonation with MSHR is intrinsically unstable and will develop to a new mode. It is found that in the mixtures with mu lti-stage heat release the steady structure on the scales predicted by the ZND theory cannot exist and evolves into a detonation wave with much thinner structure through the particular paths via which the ZND detonation losses its stability. For different MSHR features induced by CO₂ addition, two detonation development modes with double- and single-head structures are observed, with the former controlled by the merging of second- and third-stage heat release, while the latter triggered by the second-stage heat release with the fastest heat release rate.