Monday, August 23, 2010

space shuttle orbiter

A jet engine noise reduction device called a chevron, now in use on commercial airliners, is a good example of a NASA-developed technology that climbed the TRL scale to success, said Fay Collier, manager of NASA's Environmentally Responsible Aviation Project.

Chevrons are the saw-tooth pattern that can be seen on the trailing edges of some jet engine nozzles. As hot air from the engine core mixes with cooler air blowing through the engine fan, the jagged edges serve to smooth the mixing, which reduces turbulence that creates noise.

The new Boeing 787 is among the most modern jets relying on chevrons to reduce engine noise levels, sporting chevrons on the nacelles, or fan housings. The Boeing 747-8 has chevrons on both the nacelles and inner core engine nozzles.

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