Modeling of nitrogen and oxygen recombination on partial catalytic surfaces

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Modeling of nitrogen and oxygen recombination on partial catalytic surfaces

Deutschmann, O. / Riedel, U. / Warnatz, J.

The consideration of heat flux measurements as well as atom density measurements for oxygen and nitrogen atom recombination on re-entry vehicle wall (RCG coated) allows to study two recombination processes (LH and ER mechanism). On that basis, a detailed surface reaction mechanism including rate expressions for O and N atom recombination on the surfaces is established. To test the model and for a more detailed determination of rate coefficients, the computer code SPIN simulating a stagnation flow field is used. A quantitative agreement could be achieved between simulated recombination coefficients and those calculated from experiments. The complex temperature dependence of the recombination coefficients are explained by elementary reaction processes. The surface reaction scheme proposed was implemented in a two-dimensional Navier-Stokes code solving a re-entry problem. The oxygen and nitrogen profiles as well as the wall temperature were changed considerably in the region close to the body due to partial catalytic effects. Therefore, a finite rate surface chemistry should be included in the numerical prediction of hypersonic flow fields.