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Author ORCID Identifier
https://orcid.org/0000-0003-1439-930X
Date Available
8-5-2027
Year of Publication
2026
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
College
Engineering
Department/School/Program
Mechanical Engineering
Faculty
Alexandre Martin
Faculty
Savio Poovathingal
Faculty
Jonathan Wenk
Abstract
In the extreme thermal environment associated with hypersonic travel, vehicles are equipped with carbon-carbon composites as the outermost layer of their structure to withstand high heat fluxes and protect the vehicle’s interior structure. Although excellent at thermal management, under sufficiently extreme conditions, the carbon surface will heat up and react with oxygen in the atmosphere, losing mass through oxidation. In addition, this oxidation can lead to other mass-removal mechanisms, such as spallation, in which fibers of the carbon material are broken due to mechanical forces induced by the flow. When designing a thermal protection system (TPS) for a hypersonic vehicle, the thickness of the Carbon-Carbon surface becomes a critical design factor.
A better understanding of the oxidation process is therefore necessary to optimize thermal protection system (TPS) designs. Over the decades, strides have been made to better model the carbon oxidation process. Several models have been proposed, each one attempting to improve on the previous to varying degrees of success. The latest of these models is the air-carbon ablation (ACA) model. A major issue is that no single model has achieved reasonable agreement across a wide range of experimental outcomes.
Starting with the ACA model, a framework to create more robust carbon oxidation models is examined. The ACA model lacks backward rates for most reactions, which calls into question its thermodynamic consistency. It is shown that the original ACA model cannot recover the air-carbon equilibrium in an idealized 0-D chemicalreactor simulation. The process of modifying the ACA model through additional reactions and equilibrium constants demonstrates the work necessary to achieve a thermodynamically robust carbon oxidation model.
To better understand the effects of the modified ACA model and how it compares to the original, simulations based on experiments conducted in Sandia’s hypersonic shock tunnel (HST) show that the inclusion of backward rates may yield different outcomes, particularly at lower temperatures. Simulations of a notional spherecone under representative flight conditions also show how differences between models may manifest and how they may influence the design process.
Finally, a framework that connects oxidation to spallation is presented. Carbon recession rates across the surface are utilized to characterize the fiber protrusion that may occur due to differential oxidation. Then shear and pressure gradients across the surface are used in a moment balance at the base of the fiber to determine whether the resultant stresses are enough to break. Data across the surface from simulations of experiments conducted at NASA’s HyMETS arc-jet facility is used to determine how well the model’s predictive capabilities compare to data and analysis of the experimental campaign.
Digital Object Identifier (DOI)
https://doi.org/10.13023/etd.2026.405
Archival?
Archival
Funding Information
This work is supported by the Office of Naval Research (ONR) through the STTR program under contract number N6833523C0387 since 2023.
Recommended Citation
Barrios-Lobelle, Ares A., "Analysis of carbon oxidation modeling on ablation predictions" (2026). University of Kentucky Doctoral Dissertations. 865.
https://uknowledge.uky.edu/gradschool_diss/865
Included in
Aerodynamics and Fluid Mechanics Commons, Heat Transfer, Combustion Commons, Space Vehicles Commons, Structures and Materials Commons
