Damiano Baccarella, an assistant professor in the Department of Mechanical and Aerospace Engineering at the University of Tennessee, Knoxville, has received a $750,000 NASA Early Career Faculty Award to further his research on the extreme environments that hypersonic spacecraft and missiles encounter during atmospheric re-entry.
Baccarella is one of seven recipients nationwide.
The extremely high temperatures and speeds associated with hypersonic travel cause changes in air properties. These changes threaten the integrity of the craft and also cause communication blackouts during atmospheric re-entry.
Engineers like Baccarella have long used a particular type of hypersonic wind tunnel, known as an “arcjet tunnel,” to simulate the conditions produced by the extreme heat and speed of atmospheric re-entry. Materials used to produce spacecraft are tested in these tunnels.
But wind tunnel testing isn’t perfect. Conditions in the tunnels can’t be precisely measured. And scientists know the tunnels don’t exactly mirror those conditions encountered by spacecraft during re-entry.
That’s why industry uses test results but adds a margin of safety during construction.
“That’s a cost, especially when trying to scale up space travel,” Baccarella said.
The goal of the NASA-funded work is to use emerging technologies to get a more precise read on the conditions produced in the tunnels. This will give aerospace and defense industries added confidence in material testing, Baccarella said.
The UT campus is one of the few universities nationwide that has a wind tunnel built for such research.
Currently, there is one small-scale tunnel inside Baccarella’s lab on UT Drive. A second one—which Baccarella said will be “much larger and more relevant”— is under construction in the Dougherty Engineering Building. A collaboration with UT Space Institute, this second tunnel is funded by a $17.8 million grant from the U.S. Air Force through the Air Force Research Laboratory. It should be completed by the end of the year.
Baccarella said the goal is to eventually build a third tunnel at UT Space Institute.
Baccarella’s NASA-funded research will begin at the existing tunnel and continue at the second tunnel when it opens. The project—“Application of Resonance Enhanced Multi-Photon Ionization Diagnostics to the Characterization of Arcjet Flows”—aims to advance the current understanding of non-equilibrium effects in high-enthalpy hypersonic wind tunnels, by developing novel strategies for experimental characterization of chemical and vibrational non-equilibrium.
Baccarella explains: “The air we live in is in equilibrium. We can accurately predict all of its properties. That’s not the case in a high-speed and high-temperature environment.”
Because of non-equilibrium, to know how closely the test tunnels are replicating atmospheric re-entry conditions, “every single parameter of air flow has to be individually measured,” Baccarella said.
The research will employ “non-intrusive” laser technologies developed by Baccarella’s colleague and collaborator Zhili Zhang, the B. Ray Thompson Professor in MAE , to study the way air molecules vibrate, rotate, and break apart in the simulated conditions in the tunnel.
At UT since 2019, Baccarella was elected as an associate fellow of the American Institute of Aeronautics and Astronautics’s Class of 2026. He received a 2020 Air Force Office of Scientific Research Young Investigator Program (YIP) Award.
Baccarella earned his master’s degree from the University of Pisa, Italy, and his doctorate at the University of Illinois at Urbana-Champaign.