91�ؿ�

The Department of Mechanical, Materials, and Aerospace Engineering presents its MMAE 593 seminar series featuring guest speaker Francesco Panerai, assistant professor of aerospace engineering at the University of 91�ؿ� at Urbana-Champaign. Panerai will present “Insights into Carbon Ablation Mechanisms from X-Ray Imaging and Plasma Wind Tunnel Experiments.” This event is open to the public and will take place on Wednesday, February 11, from 12:45–1:45 p.m. in Room 104 of the Stuart Building.

Abstract

The problem of carbon ablation remains a key challenge in the pursuit of hypersonic flight. Carbon fiber composites are a primary material choice in thermal protection, owing to the superior thermomechanical properties of carbon and the ability to tailor material formulations with carbon, ceramic, or polymeric matrices based on flight conditions. The gasification of carbon by oxygen leads to mass loss and recession, which are design drivers for the thermal protection system and profoundly impact vehicle aerodynamics. In this work we discuss two recent experiments that provide new insights into the ablation of carbon fiber materials at extreme temperatures. The first experiment uses high-resolution, high-speed X-ray imaging to resolve competing transport-kinetics regimes during high temperature oxidation of porous carbon ablators. We discuss the key role of microstructure in the ablation process and highlight failure mechanisms at moderate temperatures. The second experiment investigates how oxygen influences ablation in plasma wind tunnel conditions. A direct comparison of ablation under supersonic air and nitrogen plasmas shows that in the absence of oxygen material erosion is highly unsteady. Carbonaceous products from nitridation and sublimation deposit at the surface and abate permeability, build up internal pressure, and trigger intermittent spallation events that can contribute up to 45 percent of the total mass loss. In air plasma, oxidation prevents such deposits from occurring by consuming gaseous carbon. Together, these experiments highlight the complex coupling between transport, sublimation, surface deposition, internal pressure, and carbon–oxygen chemistry, advancing our understanding of high-temperature ablation in carbon-based materials.

Biography

Francesco Panerai is an assistant professor of aerospace engineering at the University of 91�ؿ� at Urbana-Champaign. His research covers advanced materials for extreme environments, transport in porous media, and hypersonic aerothermodynamics. Prior to working at UIUC, he was a research scientist at NASA Ames Research Center. He received his Ph.D. and research master’s in aeronautics and aerospace from von Karman Institute for Fluid Dynamics (Belgium), and his M.S. and B.S. in mechanical engineering from the University of Perugia (Italy). He is a recipient of the 2019 Air Force Young Investigator Award and is an AIAA Associate Fellow. He is also one of the founding members of the Center for Hypersonics and Entry Systems Studies (CHESS) at UIUC.