Yacine Babou

Predictions of nonequilibrium radiation: analysis and comparison with EAST experiments

We simulate the relaxation processes behind a strong shock by means of an electronically specific collisional radiative model for atomic species. Test conditions are taken from the experimental campaign carried out in the EAST facility in the framework of the NASA Crew Exploration Vehicle Aeroscience Project. The present work is committed to the partial validation of the collisional-radiative model against the recent experimental data. A direct comparison among experimental and simulated radiative intensity profiles shows a reasonable agreement even for the low pressure cases where the flow is in strong nonequilibrium condition. In the rapidly ionizing regime behind strong shock waves, the electronic energy level populations depart from Boltzmann distributions since the high lying bound electronic states are depleted. A detailed analysis of the elementary kinetic processes occurring in the relaxation zone revealed that improvement of the agreement among simulation and experiments can be obtained using the recent rate constant compiled by Frost et al..

CO and C2 excited states relaxation in CO2 plasmas derived from a Collisional-Radiative model

In order to explain the behavior of the main excited electronic states of CO and C2 molecules formed in CO2 entry or ground test facilities plasmas, a time-dependent Collisional-Radiative (CR) model is elaborated. This CR model is then included in the general balance equation of the species to give an insight on the influence of the transport and elementary processes. The related flows are generally observed under relatively low temperature owing to the numerous internal degrees of freedom to be excited, leading to a rather weak ionization degree. The electron-induced processes are even so taken into account: their influence is studied and commented. The conditions to reach non-equilibrium steady states and the related characteristic time scales are discussed as well.

Predictions of excited states population densities using the CoRaM-CO 2 code and confrontations with measurements obtained with the VKI-Plasmatron high enthalpy wind tunnel

ow conditions, the analysis of the non equilibrium is performed. We put forward the important role of the radiation. These results are then confronted with experimental ones obtained in the VKI Plasmatron high enthalpy wind tunnel: the inuence of electrons and the limitations of our approach are discussed.