N.C. A&T Researchers Create Breakthrough to Reduce Aircraft Engine Noise

EAST GREENSBORO, N.C. (Dec. 12, 2024) – Rockets can be heard as far as 15 miles away from their launch site. Jet planes and military aircrafts can be as loud as 150 decibels at takeoff, loud enough to rupture an eardrum. Similarly, highway noise annoys neighbors.

Researchers in the Center for Composite Materials Research (CCMR) in the Department of Mechanical Engineering at North Carolina Agricultural and Technical State University’s College of Engineering (COE) have envisioned, designed, fabricated and successfully tested the first-ever lightweight high-temperature acoustic liner on NASA Glenn Research Center’s DGEN380 Engines’ exhaust section.

The high-temperature acoustic liner was subjected to rigorous testing at NASA Glenn’s Aero-Acoustic Propulsion Laboratory. During these tests, the exhaust gas temperature was raised to 700°C — an impressive feat in itself, as conventional acoustic materials struggle to maintain integrity and performance beyond 250 ⁰C. Despite the harsh conditions, the liner maintained its structural integrity leading to a significant leap forward in acoustic technology.

“The idea was envisioned in 2009. We made some samples and shared them with some national labs but could not interpret the results properly,” said Kunigal Shivakumar, Ph.D., CCMR director.

The work resumed in 2017, when Bharath Kenchappa, Ph.D., joined A&T for his doctoral program and with the help of the Navy in procuring the test equipment. A new Ph.D.-level course was introduced, and the work was revamped. The validation of the idea, design and analysis was Kenchappa’s Ph.D. work. This was first field tested on NASA’s Advanced Noise Control Fan engine for the inlet section.

“The results surprised us all,” Shivakumar said. “Encouraged by this success we extended the application to the high-temperature section, DGEN 380 exhaust, where the temperature can exceed 700 ⁰C. No successful technology exists for these temperatures. This revolutionary technology could pave the way for even higher-performing acoustic liners, potentially extending the use in a wide range of aerospace applications, from commercial jetliners to military aircraft.”

The design not only enhances the efficiency of the liner at extreme temperatures but also contributes to the broader goal of reducing environmental noise pollution from aviation. The reduction in exhaust noise could lead to quieter engines, improving the overall environmental footprint of air travel — a critical factor as the aviation industry seeks to meet stricter noise regulations and environmental standards.

“I am always impressed but never surprised by what our researchers can do,” said Stephanie Luster-Teasley Pass, Ph.D., COE dean. “When we conduct interdisciplinary work, we prove every time how important it is to have diversity of thought and skill in the room. We are consistently proud of the work that Dr. Shivakumar’s group and our Center for Composite Materials Research do.”