Aerospace engineers at the University of Cincinnati and the Naval Research Laboratory have come up with a new nozzle design for F-18 fighter planes they hope will dampen the deafening roar of the engines without hindering performance.
Distinguished professor Ephraim Gutmark, an Ohio Eminent Scholar, and his students in UC’s College of Engineering and Applied Science designed and tested the new nozzles on 1/28th-scale jet engines in his aeroacoustics lab.
The interior of the nozzles features triangular fins like rows of shark teeth that significantly reduced jet engine noise in UC lab tests. The project is a collaboration between UC, the U.S. Naval Research Laboratory, and Naval Air Station Patuxent River. This fall NAVAIR will test the UC designs and performance on F-18 Super Hornets, the tactical fighter plane used by the U.S. Marines and Navy.
Lasers illuminate the plume of a scale-model jet engine used aboard F-18 Super Hornets. UC developed a new engine nozzle that muffles the noise from jet engines without hindering performance. Credit: Andrew Higley/UC Creative + Brand
“They’re simple attachments that change the behavior of the flow coming out of the engine with minimal effect on its performance,” Gutmark said.
UC’s lab tests showed the new nozzle could reduce engine noise by between 5 and 8 decibels. That might not seem like much. But unlike linear scales like a ruler where an inch is always an inch, decibels are measured in a logarithmic scale in which 20 decibels is tenfold louder noise.
“That’s very significant,” Gutmark said. “Typically, engine companies are happy even getting a half-decibel improvement because decibels represent a logarithmic scale.”
