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

• Published in: Plasma processes and polymers Vol. 20; no. 5
• Main Authors: Khaji, Maryam, Degrez, Gérard, Mullen, Joost
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01.05.2023
• Subjects: Afterglows; Ar admixtures; Carbon dioxide; CO2 dissociation; nonequilibrium; Numerical models; plasma; Positive feedback; shock‐free; supersonic expansion; Supersonic nozzles; Vibrational states
• ISSN: 1612-8850; 1612-8869
• DOI: 10.1002/ppap.202200189

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 CO 2 ${\mathrm{CO}}_{2}$ dissociation, enhances the cooling potential. This results in positive feedback boosting the CO 2 ${\mathrm{CO}}_{2}$ 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 CO 2 ${\mathrm{CO}}_{2}$ 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 CO 2 ${\mathrm{CO}}_{2}$ 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. 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 CO 2 ${\mathrm{CO}}_{2}$ dissociation, enhances the cooling potential. This results in positive feedback boosting the CO 2 ${\mathrm{CO}}_{2}$ dissociation. Moreover, it will be seen that an additional dissociation can be obtained by adding Ar before the expansion. Two different models are used: a self‐consistent full‐numerical approach and a fast semi‐analytical approach of acceptable accuracy.