Modeling of a CO2-N2 plasma flow in a supersonic arcjet facility

The Martian-type CO2-N-2 plasma How obtained in the plasma generator of the SR5 arcjet facility has been simulated using two complementary fluid descriptions. An inviscid multitemperature monofluid description has firstly been used to evaluate the importance of the different chemical and exchange processes between the flow species. Then, a one-temperature Navier-Stokes description has been used to evaluate the influence of viscous and rarefaction effects. In the nozzle throat region, heat addition from the arc firstly leads to the establishment of a translation-vibration disequilibrium. Near the end of the nozzle throat, temperature and pressure increases allow more efficient exchange processes and lower this disequilibrium. In the nozzle diverging region, chemical and vibrational processes are quickly frozen as the flow strongly expands. Furthermore, a translation-rotation disequilibrium also occurs near the nozzle exit. Navier-Stokes simulation results evidence a quick increase of the diverging section boundary layers, and therefore most of the diverging section is in a fully viscous interaction regime. Moreover, rarefaction effects are predicted to appear near the nozzle exit walls. The experimental measurements carried near the nozzle exit confirm the thermal disequilibrium regime of the flow, predicted by the simulation results.