WRIGHT-PATTERSON AFB, OH. — A chance combination of two technologies has led to a promising new patent for the Department of the Air Force (DAF). U.S. Patent #11,454,171 B1 Turbine Cooling Engine Cooling System with Energy Separation addresses the challenge of keeping the gas turbine engines in jets from overheating, which can allow them to stay in the air longer while covering greater distances.
This patent is the result of a collaboration between LtCol Matthew Fuqua, who was with the Air Force Institute of Technology (AFIT) and Deputy Chief of the Air Force Research Laboratory’s (AFRL) Aerospace Systems Directorate Turbine Engine Division (RQT) at the time, LtCol (retired) James Rutledge of AFIT, and Capt Carol Bryant then of AFRL/RQT and now of the United States Air Force Academy (USAFA). Fuqua said the collaboration came about in part because of his thirst for knowledge.
“One cumulative effect I’ve found is that you get comfortable learning new concepts, asking ‘dumb’ questions, and keeping your eye on technology applications,” he explained. “When I was at AFIT, I decided that I wanted to pursue research in jet engine propulsion. A particular segment to that field is film cooling (for turbine engines).”
Fuqua had learned of the concept of vortex tubes – which separate compressed air into hot or cool air streams -- shortly before joining AFIT.
“I first learned of vortex tubes by chance in a thermodynamics text, which piqued my curiosity regarding the underlying physical phenomenon of temperature separation. When I joined the research group for the film coolant, they were serendipitously also playing around with vortex tubes. We came up with this idea that we could use the (concept of) the vortex tubes to permit better cooling of the turbine blade,” Fuqua said.
That coincidental intersection of technologies became the genesis of the patent.
Rotating turbine blades are housed downstream from the combustor. The blades require cooling systems to prevent parts from failing or breaking under the under the significant stress and the extreme heat they endure. Other approaches to combat this phenomenon have been tried, but they have their limitations.
“There are some things you can do with material technologies where you can make the blades out of exotic materials like high-temperature metal alloys. That can get you so far in terms of the engine surviving the environment,” Fuqua said.
The team’s proposed design incorporates vortex tubes into the cooling architecture of the turbine blades. This permits turbine designers to direct cooler cooling air to regions that need it most and optimize the use of valuable cooling air across this essential engine section. It’s easy to imagine how such a concept could save the DAF and American taxpayers a considerable amount of money. Fuqua says that further development of the concept will help to quantify that estimate and ascertain the potential savings. “Building this up to higher technology readiness levels (would be important) to assess that,” he explained.
Aside from turbine engines, the team’s work has resulted in additional benefits to the Department of Defense (DoD) and the science and engineering fields overall.
“The research involved in developing this invention has been the impetus for other innovations in surprising ways, some of which will probably continue to be incubated in the academic sphere before transitioning to the military and commercial sectors,” Fuqua said. “For example, we now know more about vortex tubes than we ever thought possible, including an understanding of how they work and their fascinating heat transfer characteristics. The breakthroughs here show that there’s a lot more space for innovation.”
The team found allies in the AFRL and Air Force Materiel Command (AFMC) Intellectual Property Law Division (LOJAZ) who helped them make sense of the patent process. That interaction with LOJAZ buoyed the team’s confidence in their research.
“We flipped a lot of the normal applications of related technologies on their heads by asking, and then rigorously answering, a lot of ‘what if’ questions that nobody had asked before,” Fuqua said. “Fortunately, the Air Force legal office was very supportive through the drafting and revision process for the patent. I’d encourage our Air Force innovators to reach out to their corresponding offices if they think they have patentable ideas.”
United States Patent Office Patent: #11,454,171 B1
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