Detailed and Simplified Kinetic Schemes for High Enthalpy Air Flows and Their Influence on Catalycity Studies
Abstract
The thorough understanding of the formation and the relaxation of the plasma produced in the shock layer developed during the re-entry of a spacecraft in the upper layers of the earth's atmosphere is crucial in order to prevent damaging of its outer surface. Among the different points to be studied, the chemical aspects are particularly important: the mechanical characteristic time scale of the flow being short, the flow is indeed in chemical nonequilibrium. In addition, the inner storage of energy of the different species of the flow leads to other mechanical behaviors than those observed in classical low temperature flows. These nonequilibrium effects have to be taken into account accurately in codes devoted to the study of the interaction between the plasma and the surface. In this paper, we propose to focus our attention on the detailed kinetics of an air plasma under nonequilibrium conditions. First, we present a time-dependent collisional-radiative (CR) model for atomic oxygen to study in detail ionization and three-body recombination rates of oxygen in high temperature air plasma flows. Second we present a time-dependent CR model for air taking into account 13 species and numerous excited states and working over a wide range of pressure and temperature. For typical conditions encountered in reentry flows, we compare this detailed CR scheme for air with simplified schemes (proposed by Park, Dunn & Kang and Gupta et al.) usually implemented in high enthalpy air flow codes. Finally, a 1D code simulating the stagnation point boundary layer near the wall of the spacecraft is presented and the influence of the gas chemistry on the wall catalycity is discussed.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 08, 2006
- Accession Number
- ADA476906
Entities
People
- Anne Bourdon
- Arnaud Bultel