Self-consistent modeling of the flow-chemistry interplay in supersonically expanding CO2 mixtures; positive feedback of flow properties in supporting dissociation

A self-consistent model giving insights on the flow-chemistry interplay in supersonic nozzles is presented. It is shown that the change of flow properties, caused by CO2 ${\mathrm{CO}}_{2}$ dissociation, enhances the cooling potential. This results in positive feedback boosting the CO2 ${\mathrm{CO}}_{2}$ dissociation. The focus of this study is on the second stage of a tandem-construction, that is, the expanding afterglow. The first stage of activating the CO2 ${\mathrm{CO}}_{2}$ vibrational states can be done by combustion or a plasma treatment. The expansion in the second stage triggers the vibrational-vibrational ladder-climbing mechanism favorable for CO2 ${\mathrm{CO}}_{2}$ dissociation. It is seen that an additional dissociation can be obtained by adding Ar before the expansion. Two different model types are used: a self-consistent full-numerical model and a fast semi-analytical approach of acceptable accuracy.