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Old 07-10-2012, 02:52 PM   #14 (permalink)
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Boeing is making a big claim on those winglets: 5.5% better FE!

Boeing's New Double-Edged Winglet Saves Gas, Looks Awesome || Jaunted

The trailing edge on those turbofans looks pretty cool too. Are those VGs for noise reduction? Why yes, yes they are:
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.
They under describe them a bit. I found elsewhere that they are, in fact VGs. So all you trailing edge VGers can now claim that your VGs are really, actually, for noise reduction.

From:Aerospace Technology: Technology Readiness Levels Demystified08.20.10

Also they are working on air injection VGs for noise reduction:Fluidic Chevrons for Jet Noise Reduction

Last edited by orange4boy; 07-10-2012 at 03:11 PM..
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