Date Available


Year of Publication


Degree Name

Master of Science in Aerospace Engineering (MSAeroE)

Document Type

Master's Thesis




Mechanical Engineering

First Advisor

Michael Renfro


A flow apparatus for determining the Darcy permeability and Klinkenberg molecular slip adjustment parameter in arbitrary porous media was created. Two leak-proof methods were developed to secure samples of porous media in the flow apparatus independent of surface irregularities, structural integrity, or material porosity. The first of these methods uses thermoset resin casting to permit material samples of a highly irregular profile to be studied. The second method utilizes heat-shrink polyolefin tubing to create a wall seal while preserving the exposed faces of a given cylindrical sample, enabling the study of inhomogeneous surface features. These methods were used to characterize the permeability and slip factor for several ablative spacecraft thermal protection system materials using nitrogen gas at pressures up to 1.3 atmospheres in ambient temperatures. Materials were characterized in the virgin state and in various states of thermal decomposition after heating in both an oxidizing and a non-oxidizing environment. Certain materials were observed to undergo a smooth and consistent increase in permeability with an accompanying decrease in the Klinkenberg factor as decomposition progressed, while other materials demonstrated a similar trend but with high amounts of noise or an abrupt upwards jump in permeability at advanced levels of decomposition.

Digital Object Identifier (DOI)

Funding Information

“Measurement of permeability and tortuosity for charred TPS samples,” National Aeronautics and Space Administration Kentucky Space Grant, 8/15/22-9/30/23.

“KRUPS-AMTSP: Additive manufacturing of thermal protection systems,” National Aeronautics and Space Administration, 8/1/21-11/24/23.

“A stochastic approach to permeability and tortuosity modeling using experimental flow tube measurements,” National Aeronautics and Space Administration Kentucky – Established Program to Stimulate Competitive Research, 1/1/21-12/31/21.

Available for download on Thursday, September 19, 2024