Professor Schwartzenruber awarded AFOSR grant to study energy transfer on hypersonic vehicles
AEM Professor Thomas Schwartzentruber has recently been awarded a large grant from the Air Force Office of Scientific Research (AFOSR). The funded project, “Reduced Heat Flux Through Preferential Surface Reactions Leading to Vibrationally and Electronically Excited Product States,” seeks to understand the fundamental mechanisms by which energy (heat) is transferred to the surface of a hypersonic vehicle.
Professor Schwartzentruber is the Principal Investigator (PI) for the project. Other researchers involved in the project are Professor Donald Truhlar (as a Co-PI) of the Department of Chemistry, and two subcontractors from SRI International in Menlo Park, CA: Dr. Jochen Marschall and Dr. Richard Copeland. The project has been granted a $1.7 million budget over a three-year period. A summary of the research is outlined below:
Through this research we seek to understand the fundamental mechanisms by which energy (heat) is transferred to the surface of a hypersonic vehicle. New concepts for hypersonic Air Force vehicles (flying faster than Mach 5) will induce extreme heating conditions for which new heat shield designs are required. 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.
More specifically, it has been observed experimentally that oxygen atoms can recombine on silica-based heat shields to form oxygen molecules in electronically excited states. 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. At the most fundamental level, Truhlar’s group will investigate oxygen-silica reactions with electronic excitation, and 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.