Direct detonation initiation: A comparison between the critical curvature and critical decay rate models

The present study compares the critical initiation energy predicted by the critical curvature (CC) and critical decay rate (CDR) models. To ensure a fair and meaningful comparison between these two theoretical approaches, the Taylor-Sedov blast wave model, which enables us to relate the critical state to the energy of the point source, has been employed in both models. Simplified as well as detailed chemical mechanisms were employed for the comparison. By using the same blast wave model, the ratio of critical initiation energy calculated with the CC and CDR models was found to be one to two orders of magnitude smaller than the results in previous studies. Although the choice of the blast wave model is important, the critical energy predicted by the CC model is invariably larger than the one predicted by the CDR model. This was explained by analyzing the relationship between the shock front radius and decay time, as well as the ignition delay-time around the critical conditions of the two models. It was demonstrated that the critical conditions of the CDR model can be fulfilled more easily than those of the CC model. As a result, the main source of discrepancy between the CDR and CC models is that they adopt different initiation failure mechanisms, namely, curvature for the CC model against unsteadiness for the CDR model. Published under an exclusive license by AIP Publishing.