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

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

“…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).…”

“…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.…”

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

“…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).…”

“…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].…”