UT-Knoxville researchers receive $17.8M to create hypersonic ‘wind tunnel’ for aerospace materials testing

A UT team secured funding for a $17.8 million grant from the U.S. Air Force to create a wind tunnel that can subject samples of materials like high-temperature ceramics to hypersonic conditions.

Researchers at the University of Tennessee in Knoxville will use a $17.8 million grant from the U.S. Air Force to create a wind tunnel to recreate hypersonic conditions for aerospace research, a recent announcement said.

According to a news release from the university, the new wind tunnel will be housed at the UT Space Institute in Tullahoma, Tennessee, and will join only a handful in the world that can mimic the conditions of hypersonic flight.

Researchers said the project is crucial to the future development of hypersonic vehicles such as space shuttles, which hit Earth’s atmosphere at nearly Mach 25.  The most vulnerable parts of these vehicles, such as the nose and leading edges of wings, are covered in specialized heat-resistant materials called “the thermal protection system” (TPS) to protect against the heat created at those speeds.

“The TPS is not continuous. Every joint between tiles, and even the glue that sticks the TPS to the fuselage, is a weakness,” Jacqueline Johnson, a materials scientist and aerospace engineering professor at UTSI, said in a public statement.

 “We have had two glaring examples of what happens when the TPS is weak or damaged in the Challenger and Columbia space shuttle disasters.”

According to the announcement, the new wind tunnel will alleviate the yearslong waiting list for these advanced facilities. The project will “establish expertise and capabilities” in fabrication, testing, and evaluation of new materials for use in extreme engineering environments.

“We have all these different kinds of wind tunnels that each specialize in examining some aspect of hypersonic flight — aerodynamics, gas chemistry, material degradation during flight — but nobody has the capability to replicate full hypersonic flight conditions,” MABE Assistant Professor Mark Gragston said in a statement. “There’s a big market for increased testing capability in academic research because that’s where new materials are being developed.”

“We know this skillset and knowledge are desired by industry partners working in hypersonic system development,” he added. “Developing a capable workforce is a crucial step in improving the scale economy for these materials and is in line with current initiatives led by the government and industry.”

The university announcement said the $17.8 million project, funded by the U.S. Air Force through the Air Force Research Laboratory in Ohio, will be headed by Johnson and MABE Assistant Professor Damiano Baccarella, an expert in hypersonic aerothermodynamics who has previously overseen construction of a hypersonic wind tunnel. They will be joined by four other investigators from UT and the University of Dayton Research Institute.

“This team was carefully chosen to bring different aspects together, and nobody is trying to be the boss,” Johnson said. “There’s a lot of work to do, and it cannot be done by UTSI alone.”

Moving forward, the announcement said, the research team will oversee the construction of an unparalleled hypersonic wind tunnel facility. The team is also working to validate and improve simulations of TPS materials in order to “close the gap between ground-based tests and flight conditions.” Researchers said these simulations will benefit from testing capabilities at UTSI, such as noninvasive laser-based analysis of the chemical reactions around materials during testing.

“We have more advanced measurement capabilities at UT than what is usually available in the facilities at Arnold Engineering Development Complex  at Arnold Air Force Base or at the National Aeronautics and Space Administration,” Gragston said. “We’re going to be applying many of them to this hypersonic testing environment for the first time.”

The grant will also enable graduate students to work under each of the participating investigators. The students will advance TPS material research and gain an understanding of the infrastructure behind a hypersonics facility, according to the announcement.

“There are several types of hypersonics facilities, and you can learn how to build all of them from textbooks except for this kind,” Gragston said. “The students who are around while this is being built, and are helping build it, will have a truly unique opportunity.”

For more information on the research and grant, visit news.utk.edu.