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$1.7M grant focuses on heat shields for hypersonic vehicles

Department of Chemistry Regents Professor Donald Truhlar is co-principal investigator of a $1.704 million grant from the Air Force Office of Scientific Research, conducting research critical to the development of new heat shields for hypersonic vehicles.

Principal investigator is Assistant Professor Thomas Schwartzentruber from the Department of Aerospace Engineering & Mechanics. The grant is over three years and starts, October 1.

"Through this research, we seek to understand the fundamental mechanisms by which energy (heat) is transferred to the surface of hypersonic vehicles," said Truhlar. He is a world leader in the theoretical and computational methods that describe the potentials and dynamics of molecule-to-molecule and molecule-to-surface collisions.

He explained that new concepts for hypersonic Air Force vehicles flying faster than Mach 5 will induce extreme heating conditions requiring new heat shield designs. The air in front of the vehicle gets so hot that air molecules break into atoms. These atoms can diffuse through the boundary layer and exothermically react with the heat shield surface, depositing significant energy to the vehicle. The long-term goal is to understand these gas-surface reactions at the molecular level so that new materials can be tailored to control the energy transfer between a high temperature gas and the heat shield surface.

It has been observed experimentally that oxygen atoms can recombine on silica-based heat shields to form oxygen molecules in electronically excited states, Truhlar said. Such states are long-lived in the gas phase and may serve to lock-up significant energy, which is carried away from the vehicle and thus not transmitted to the surface.

An experimental setup will be designed and definitive experimental evaluation of the production of excited oxygen molecules resulting from oxygen-atom surface recombination will be performed at SRI’s laboratory in Menlo Park, CA. Truhlar’s research group will investigate oxygen-silica reactions with electronic excitation. Schwartzentruber’s group will provide the modeling link between quantum chemistry and experiment using large-scale stochastic particle simulations of the full experimental environment. The objective is to fully explain this gas-surface reaction phenomenon at the most fundamental level with the potential to impact future heat shield design and capability for high-speed vehicles.