Finite-rate oxidation model for carbon surfaces from molecular beam experiments

Savio Poovathingal, Thomas E. Schwartzentruber, Vanessa J. Murray, Timothy K. Minton, Graham V. Candler

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Scopus citations

Abstract

An oxidation model for carbon surfaces is developed where the gas-surface reaction mechanisms and corresponding rate parameters are based solely on observations from recent molecular beam experiments. In the experiments, a high energy beam of oxygen (93% atoms and 7% molecules) was directed at a high-temperature carbon surface. The measurements revealed that CO was the dominant reaction product and that its formation required a high surface coverage of oxygen atoms. As the carbon sample temperature was increased during the experiment, the surface coverage was reduced and the production of CO diminished. Most importantly, the measured time-of-flight distributions of surface reaction products indicated that CO and CO2 were predominately formed through thermal reaction mechanisms and not impulsive reactive scattering. These observations enabled the formulation of a finite-rate oxidation model including surface-coverage dependence, similar to existing finite-rate models used in computational fluid dynamics (CFD) simulations. However, each reaction mechanism and all rate parameters of the new model are determined individually based on the molecular beam data. The new model is compared to existing models using both zero-dimensional gas-surface simulations and full CFD simulations of hypersonic flow over an ablating surface. The new model predicts similar overall mass loss rates compared to existing models, however, the individual species production rates are completely different. The most notable difference is that the new model (based on molecular beam data) predicts CO as the oxidation reaction product with virtually no CO2 production, whereas existing models predict the exact opposite trend.

Original languageEnglish (US)
Title of host publication46th AIAA Thermophysics Conference
PublisherAmerican Institute of Aeronautics and Astronautics Inc, AIAA
ISBN (Print)9781624104350
StatePublished - Jan 1 2016
Event46th AIAA Thermophysics Conference, 2016 - Washington, United States
Duration: Jun 13 2016Jun 17 2016

Publication series

Name46th AIAA Thermophysics Conference

Other

Other46th AIAA Thermophysics Conference, 2016
CountryUnited States
CityWashington
Period6/13/166/17/16

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  • Cite this

    Poovathingal, S., Schwartzentruber, T. E., Murray, V. J., Minton, T. K., & Candler, G. V. (2016). Finite-rate oxidation model for carbon surfaces from molecular beam experiments. In 46th AIAA Thermophysics Conference (46th AIAA Thermophysics Conference). American Institute of Aeronautics and Astronautics Inc, AIAA.