Finite-Rate Oxidation Model for Carbon Surfaces from Molecular Beam Experiments

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

doi:10.2514/1.j055371

Cited by 67 publications

(32 citation statements)

References 43 publications

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“…Furthermore, the pulsed nature of the molecular beam led to in-depth studies of the time-varying aspects of the experiments [27] [28]. In contrast, the original model by Poovathingal et al [20] [21], assumed that the reaction products (and their relative probabilities) observed during the beam pulse would be the same as those observed if the beam were continuously operating, and the unsteady details of the measurements between pulses were not relevant to formulate an ablation model. It was also observed experimentally that the product flux (leaving the surface) captured by the mass spectrometer was not the same at high and low temperatures, despite the same molecular beam conditions (i.e., the same beam flux).…”

Section: New Molecular Beam Data and Relevance To Hypersonic Ablationmentioning

confidence: 99%

“…It was also observed experimentally that the product flux (leaving the surface) captured by the mass spectrometer was not the same at high and low temperatures, despite the same molecular beam conditions (i.e., the same beam flux). Since reaction products were observed to leave the surface thermally, the model by Poovathingal et al [20] [21] assumed that the product flux not captured by the detector had similar chemical composition as the product flux that was captured by the detector. In contrast, the model by Swaminathan-Gopalan et al [27] assumed that the product flux not captured by the detector was entirely composed of CO and that this CO was not counted because it left the surface between beam pulses.…”

Section: New Molecular Beam Data and Relevance To Hypersonic Ablationmentioning

confidence: 99%

“…The previous oxygen-carbon reaction model of Poovathingal et al [21] consisted of five reaction mechanisms:…”

Section: Model Descriptionmentioning

confidence: 99%

“…We propose that there are two types of adsorbed oxygen, a relatively weakly bound O(s) and a relatively strongly bound O * (s). Reactions (1) and 5are ing CO formation with a gas-phase dependent mechanism is important for model accuracy at high pressures, for example, similar gas-phase dependent reactions were used in the model by Poovathingal et al [21]. Reaction (4) is the gas-phase dependent CO 2 formation mechanism dependent on O(s).…”

Section: Reactions Involving Atomic Oxygen (O)mentioning

confidence: 99%

“…The experiments provided a wealth of data regarding what reactions were dominant and the reaction probabilities for different products leaving the surface. This data was used to construct a probability model for use in direct simulation Monte Carlo (DSMC) [20] and a finite-rate model for use in computational fluid dynamics (CFD) [21].…”

mentioning

confidence: 99%

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Air-Carbon Ablation Model for Hypersonic Flight from Molecular Beam Data

Prata

Minton²,

Schwartzentruber³

2020

Preprint

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Recent molecular beam experiments of high velocity O, N, and O2 impacting carbon material at high temperature produced detailed surface chemistry data relevant for carbon ablation processes. New data on O and N reactions with carbon has been published using a continuous molecular beam with lower velocity (2000 m/s) and approximately 500 times higher beam flux than previous pulsed-beam experiments. This data is interpreted to construct a new air-carbon ablation model for use in modeling carbon heat shield ablation. The new model comprises 20 reaction mechanisms describing reactions between impinging O, N, and O2 species with carbon and producing scattered products including desorbed O and N, O2 and N2 formed by surface-catalyzed recombination, as well as CO, CO2, and CN. The new model includes surface-coverage dependent reactions and exhibits non-Arrhenius reaction probability in agreement with experimental observations. All reaction mechanisms and rate coefficients are described in detail and each is supported by experimental evidence or theory. The model predicts pressure effects and is tested for a wide range of temperatures and pressures relevant to hypersonic flight. Model results are shown to agree well with available data and are shown to have significant differences compared to other models from the literature.

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Section: New Molecular Beam Data and Relevance To Hypersonic Ablationmentioning

confidence: 99%

Section: New Molecular Beam Data and Relevance To Hypersonic Ablationmentioning

confidence: 99%

“…The previous oxygen-carbon reaction model of Poovathingal et al [21] consisted of five reaction mechanisms:…”

Section: Model Descriptionmentioning

confidence: 99%

Section: Reactions Involving Atomic Oxygen (O)mentioning

confidence: 99%

mentioning

confidence: 99%

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Air-Carbon Ablation Model for Hypersonic Flight from Molecular Beam Data

Prata

Minton²,

Schwartzentruber³

2020

Preprint

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Flow Reactor Experiments of High-Temperature Graphite Oxidation and Nitridation

Anderson,

Zolfaghari,

Bhattacharya

et al. 2024

High Temperature Corrosion of mater.

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Predicting the gas-surface interactions of solid carbon is necessary for the design of many engineering systems that employ graphite. Experimental determination of the reaction rates improves the delity of those predictions. Here, we study oxidation and nitridation of graphite by thermal and non-thermal, plasma assisted processes. Experiments are conducted at a pressure of 2 kPa, higher than previous ow reactor experiments of this kind and closer to the conditions experienced in engineering applications. At these higher pressures, the limitations of mass transport and the interference between oxygen and nitrogen species become important. Reaction rates are determined from mass loss, reaction products are identi ed with mass spectrometry, and surface roughening is characterized by electron microscopy.

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