Ever wonder why the 787 engine cowlings are not smooth?

I searched the forum and couldn’t find anything about this topic. If there is already, feel free to flag and close as a duplicate.
Looking at the 787 anyone will notice that the engine covers are serrated. The article below calls them ‘chevrons’.
I always wondered, why why why. Turns out, it all has to do with noise abatement. Interesting article. Never knew that NASA had a hand in this design.

Just thought the IF community might be wondering the same thing!

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I knew about this, a lot of engines will be adopting this style of cowling but this is very intriguing to know about if you weren’t aware.

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I guess I never really thought about it until recently flying on a 787. There’s alot of engineering in the design. Sometimes the simplest things…

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New Boeing Aircrafts such as 737MAX and 777MAX are also adopting this cowling. I always wondered why they use it. Perhaps to keep the fuel efficiency (?)

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The NASA article only mentions noise reduction of the engine. It would be interesting to find something about what it does (if anything) for efficiency.

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It’s to reduce noise and increase efficiency.

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Don’t forget the 747-8s also have this!

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Have you got any info about the efficiency? I can’t find anything that says they do anything for engine efficiency… only noise reduction.

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Wonder why Airbus do not have the chevrons

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So they are pointless things really. Don’t like quiet engines, I prefer knowing when a plane is coming overhead.

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No I never wondered about it because I never noticed it…


But great for pointing out and giving detail on it.

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I think Boeing said its obsolete already because of active noise reduction.

Also, the E-jets have them on a inner part of the engine, but they’re still in plain sight.

The 777X has active noise reduction, not chevrons. @SingaporeAirlines

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You can see the chevrons painted in dark grey. Kinda hard to see but it is what it is.

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It is all about conservation of energy. All forms of travel convert energy into motion. Any losses are usually dissipated as heat/noise/vibration or other. The fact that the noise is reduced means that more energy is conserved during the combustion cycle. More noise = less efficient since the energy leakage is greater.

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Not only does the 787 Family have chevrons but also the 747, And the 737 also will have this, and the upcoming 777x will have this as well, this has nothing to do with fuel efficiency at all, engines are fuel efficient when the bypass ratio is around 10:1 which means the turbine is smaller than Engine fan meaning more air goes around it and less fuel is burned, for example the Ge engines used on the 787,748, and the 737 MAX, i am pretty sure these “Chevrons” are to reduce engine noise or just for style…

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Someone in the ANA that works on the 787 told me.

I agree that there MUST be some type of energy conservation, I’m just saying, I can’t find anything documenting that. I’m going to look some more today after work, but I can’t find anything that says the chevrons provide any type of engine efficiency improvement.

That’s a pretty cool article. I had noticed the chevrons before, but really just thought they were there more for aesthetics than anything else. Looks like I learned something else new about aviation today from the community. Thanks for sharing!

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http://www.boeing.com/news/frontiers/archive/2006/march/i_tt.html

A bit more in ref. to the efficiency improvements in this article.

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Always wondered why it looked like that. Thanks for sharing!

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