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 the exhaust section of NASA Glenn Research Center’s DGEN 380 engine.
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 250⁰C. Despite the harsh conditions, the liner maintained its structural integrity leading to a significant leap forward in acoustic technology.
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‘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, the CCMR’s director.
The work resumed in 2017, when Bharath Kenchappa joined A&T for his doctoral programme and with the help of the US Navy in procuring the test equipment. A new PhD-level course was introduced and the work was revamped. The validation of the idea, design and analysis was Kenchappa’s PhD work. This was first field tested on NASA’s Advanced Noise Control Fan engine for the inlet section.
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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 700⁰C. 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.