Molecular simulations of surface ablation using reaction probabilities from molecular beam experiments and realistic microstructure

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

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

10 Scopus citations

Abstract

Molecular simulations are performed of high temperature dissociated oxygen reacting with an idealized carbon-carbon composite material, where the microstructure is resolved. The Direct Simulation Monte Carlo (DSMC) method is used to simulate the convection and diffusion of reactants towards the microstructure and the transport of surface reaction products away from the microstructure. Simulations are performed with and without gas-phase chemical reactions in order to determine the relative importance of gas-surface reactions compared to gas-phase reactions next to the material surface. The simulations incorporate reaction probabilities for individual gas-surface collisions based on new reactive scattering data obtained in a molecular beam facility. The molecular beam experiments clearly indicate that a majority of surface reaction products were produced through thermal mechanisms. The experiments provide detailed data on the relative magnitude of O, O2, CO, and CO2 scattering from a representative material sample, made of vitreous carbon. For a gas-surface temperature of 800K, it is found from the simulations that despite CO being the dominant surface reaction product, a gas-phase exchange reaction forms significant CO2 within the microstructure region. The amount of CO2 production within the microstructure region is shown to be dependent on the local Knudsen number, based on the exposed microstructure height. Finally, preliminary simulations are performed for a real Carbon- Carbon (C-C) surface. The surface topology is obtained through X-ray microtomography of an ablated C-C sample, which is triangulated and used directly within a DSMC simulation of the gas-surface interaction.

Original languageEnglish (US)
Title of host publication53rd AIAA Aerospace Sciences Meeting
PublisherAmerican Institute of Aeronautics and Astronautics Inc, AIAA
ISBN (Print)9781624103438
DOIs
StatePublished - Jan 1 2015
Event53rd AIAA Aerospace Sciences Meeting, 2015 - Kissimmee, United States
Duration: Jan 5 2015Jan 9 2015

Publication series

Name53rd AIAA Aerospace Sciences Meeting

Other

Other53rd AIAA Aerospace Sciences Meeting, 2015
CountryUnited States
CityKissimmee
Period1/5/151/9/15

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