liedetectors
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A-321 CFM56-5 Chevrons

Mon Nov 16, 2009 4:31 am

Hello all,

I just noticed that Aeroflot's CFM-56-powered A-321, pictured in the link below, has chevrons in the vicinity of the exhaust nozzle. Does anyone know the story behind this? Is this an Airbus upgrade or a long-term test article? The next CFM56-powered 321 (of Air India) off of the line did not have chevrons.

http://www.airliners.net/photo/Aerof...Russian/Airbus-A321-211/1609608/L/
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Mir
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RE: A-321 CFM56-5 Chevrons

Mon Nov 16, 2009 5:00 am

Unrelated question (but related to the pic):

What are those two little ports about halfway up the back of the pylon for? They look like drains, but drains for what?

-Mir
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tdscanuck
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RE: A-321 CFM56-5 Chevrons

Mon Nov 16, 2009 5:04 am



Quoting Liedetectors (Thread starter):
Does anyone know the story behind this?

Unfortunately, no. I'd love to hear the inside scoop!

Quoting Mir (Reply 1):
What are those two little ports about halfway up the back of the pylon for? They look like drains, but drains for what?

I don't know for sure, but you usually have a drain in that area for the strut. At least one to let fuel/water out so it doesn't pool in the strut and probably another one for hydraulics if they've got a pump or resevoir in the fairing (not sure if the A321 does, but some aircraft do).

Tom.
 
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747classic
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RE: A-321 CFM56-5 Chevrons

Mon Nov 16, 2009 9:05 am

Quoting Tdscanuck (Reply 2):
I'd love to hear the inside scoop!

I found this article over the CFM56-5B engine, installed on the A321, on the CFM website.
The following is mentioned : "The technology being developed includes: three-dimensional aerodynamic outlet guide vanes; a core chevron nozzle; and improved reverser and inlet linings on the nacelle."

See : http://www.cfm56.com/press/news/cfm5...begins+full-scale+engine+tests/339

For further info :
http://www.aiaa.org/events/aners/Presentations/ANERS-Gliebe.pdf

[Edited 2009-11-16 01:14:16]
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oly720man
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RE: A-321 CFM56-5 Chevrons

Mon Nov 16, 2009 12:31 pm

http://www.airbus.com/store/mm_repos...dia_object_file_FAST37_p19_p22.pdf

It's an Airbus/CFM noise reduction device option that can be fitted. Could be that the noise rules in India are rather less onerous than in other places, hence the lack of them on the AI aircraft.

The more recent AF aircraft are fitted with them, though not always easy to see, e.g.

F-GTAR

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F-GTAS

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F-GTAV

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Photo © Daniel & Robert Fall

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liedetectors
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RE: A-321 CFM56-5 Chevrons

Mon Nov 16, 2009 5:43 pm

Sweet! Thanks guys for the informative replies and links!
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Fly2HMO
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RE: A-321 CFM56-5 Chevrons

Tue Nov 17, 2009 1:01 am

Hmm never seen them before. Funny that its only on the 321s, you'd think it would be available on other CFM Airbii
 
keta
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RE: A-321 CFM56-5 Chevrons

Tue Nov 17, 2009 7:01 am



Quoting FLY2HMO (Reply 6):
Hmm never seen them before. Funny that its only on the 321s, you'd think it would be available on other CFM Airbii

Right, why can't we see them in the A320? Neat feature anyway, never noticed it before!  Smile
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GPHOTO
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RE: A-321 CFM56-5 Chevrons

Tue Nov 17, 2009 7:29 am

Chevrons in the exhaust section are becoming increasingly common. For example, I noticed these two recently:


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Photo © Jim Groom



As well as reducing noise, I would be interested in any effect it might have (positive or negative)on fuel economy or thrust?

Best regards,

Jim
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keta
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RE: A-321 CFM56-5 Chevrons

Tue Nov 17, 2009 10:44 am



Quoting GPHOTO (Reply 8):
As well as reducing noise, I would be interested in any effect it might have (positive or negative)on fuel economy or thrust?

I have a figure for the fluted nozzles on the JT8D quoting 7 dB noise reduction with about 5-6% loss of thrust. This is kind of old, though; I'm pretty sure these serrations achieve better results.
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747classic
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RE: A-321 CFM56-5 Chevrons

Tue Nov 17, 2009 1:12 pm



Quoting FLY2HMO (Reply 6):
Hmm never seen them before. Funny that its only on the 321s, you'd think it would be available on other CFM Airbii

As stated in the article : http://www.airbus.com/store/mm_repos...dia_object_file_FAST37_p19_p22.pdf

The "noise package" is now standard on the A321 and an option on the other models.
The reason behind this is that the A321 (heavy weight version) doesn't comply with the new stage 4 noise limits in effect for all new aircraft, certified after 1 January 2007.
In fact this is the present noise standard, although legally not valid for the present A320 generation of aircraft, all certified before 1 januari 2007.
All other sub types of the A320 series are at or below the stage 4 noise standard and don't need the chevrons, but can be delivered as an option with this "noise package", to become even more silent.

Also stated in the article is the fact that the FADEC needs some tweaking to produce the same thrust level, so there must be a loss in efficiency somewhere.
Because this is an Airbus brochure, nothing is said about the actual loss in SFC.
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ex52tech
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RE: A-321 CFM56-5 Chevrons

Thu Nov 19, 2009 11:18 am



Quoting Mir (Reply 1):
What are those two little ports about halfway up the back of the pylon for? They look like drains, but drains for what?

Pylon drains, from different areas of the pylon, one is in the area where the lines hook up. Many airplane's pylon drains connect to the engine, and drain out of the gang drain on the engine.

The fairing just below those drains has a channel to drain any fluids out of the area in the aft section of the pylon.
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LH707330
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RE: A-321 CFM56-5 Chevrons

Fri Dec 11, 2015 6:23 pm

Thread bump: has anybody figured out how much of a fuel burn penalty these core chevrons add? I've heard that the nacelle chevrons on the 787 cost about .25%.

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