Date Available

12-13-2025

Year of Publication

2025

Document Type

Master's Thesis

Degree Name

Master of Science (MS)

College

Engineering

Department/School/Program

Mechanical Engineering

Faculty

John Maddox

Faculty

Jonathan Wenk

Abstract

Atmospheric re-entry induces intense thermal stress upon vehicles through a high-enthalpy boundary layer that encompasses the craft. To protect these vehicles, numerous insulative methods, known as thermal protection systems (TPS), are deployed to protect the craft during re-entry. The TPS materials insulate the craft from intense thermal transmission that would terminate a mission. In hypersonic environments, vast temperature gradients exist, enforcing the exponential effect of thermal radiation. However, TPS materials are commonly low-density fibrous materials that allow for the potential to be penetrated by thermal radiation. A series of arc-jet tests was completed to replicate enhanced radiative conditions in a hypersonic environment. The experimentation consisted of two methodologies with a constant enthalpy setpoint. Method one consisted of traditional arc-jet experimentation procedures, while method two required the insertion of near-infrared heaters in an arc-jet to exhibit augmented radiation conditions. Testing completed on LI2200, Lockheed Insulation, revealed minimal variance in thermal dispersion, traditional, and radiation experimentation; respectively, \SI{9.130}{\metre\per\second\squared} and \SI{9.214}{\metre\per\second\squared}. Although temperature contours recorded \SI{5}{\milli\metre} from the top surface have significant variance in local maximum and shape. Thus, LI2200 experiences a deviation of thermal performance when experiencing dominant modes of thermal transfer. In addition, steady-state testing with NIR heaters was used to simulate potential subsurface penetration modes, utilizing an augmentation of ASTM E 1225. The steady-state testing had two experimental methodologies: one that allowed potential sub-surface absorption to occur, and a mode where the main transmission occurred through conduction. When tested at the same temperature setpoint, measured at \SI{5}{\milli\metre} from the top surface, Fiberform samples exposed to surface radiation transmitted a heat flux of \SI{3034}{\watt\per\metre\squared}, whereas Fiberform exposed to solely conduction through the fibers transmitted a heat flux of \SI{4120}{\watt\per\metre\squared}. Comparatively, the significantly denser reusable TPS LI2200 transmitted a heat flux of \SI{1708}{\watt\per\metre\squared} when radiation was the dominant mode of transmission and a heat flux \SI{2796}{\watt\per\metre\squared} when conduction was the dominant mode of transmission at the same temperature setpoint.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2025.565

Funding Information

NASA Established Program to Stimulate Competitive Research 3210002819 in 2025 and NASA Established Program to Stimulate Competitive Research 3210002356 in 2024.

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