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Flameholders?  
User currently offlineLehpron From United States of America, joined Jul 2001, 7028 posts, RR: 21
Posted (8 years 9 months 3 weeks 1 day 10 hours ago) and read 2808 times:

For some reason, I have always akin the burn of fuel out of an injector to a pilot light in a commercial heating furnace. That it would always be lit unless the fuel flow stopped, but needed to be re-lit by an ignition source every time.

What are flame holders, what do they look like and how do they work? Do they store heat, so to speak.


The meaning of life is curiosity; we were put on this planet to explore opportunities.
6 replies: All unread, jump to last
 
User currently offlineMD11Engineer From Germany, joined Oct 2003, 13985 posts, RR: 62
Reply 1, posted (8 years 9 months 3 weeks 1 day 8 hours ago) and read 2684 times:

Quoting Lehpron (Thread starter):
What are flame holders, what do they look like and how do they work? Do they store heat, so to speak.

Flameholders create localised turbulence in the combustor (or the tail pipe of an engine with reheat / afterburner), which locally slows down the airflow and prevents the flame from getting blown away from the vicinity of the injector nozzles.

In afterburners they often look like rings of v shaped sheetmetal (high heat resistant steels, opening of the V faces aft) around and just downstream of the injector.

Jan


User currently offlineTripleDelta From Croatia, joined Jul 2004, 1122 posts, RR: 7
Reply 2, posted (8 years 9 months 3 weeks 1 day 8 hours ago) and read 2667 times:
AIRLINERS.NET CREW
PHOTO SCREENER

Quoting MD11Engineer (Reply 1):
Flameholders create localised turbulence in the combustor (or the tail pipe of an engine with reheat / afterburner), which locally slows down the airflow and prevents the flame from getting blown away from the vicinity of the injector nozzles.

I found this nice shot of the rear end of an F-16 engine in the db. Is this ring with the "fingers" and corrugated inner and outer radius the flameholder?

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Photo © Stephan Tophoven




No plane, no gain.
User currently offlineFredT From United Kingdom, joined Feb 2002, 2185 posts, RR: 26
Reply 3, posted (8 years 9 months 3 weeks 1 day 8 hours ago) and read 2658 times:

Quoting TripleDelta (Reply 2):
I found this nice shot of the rear end of an F-16 engine in the db. Is this ring with the "fingers" and corrugated inner and outer radius the flameholder?

From experience with other types: Yes.



I thought I was doing good trying to avoid those airport hotels... and look at me now.
User currently offlineIFIXCF6 From United States of America, joined Sep 2004, 108 posts, RR: 0
Reply 4, posted (8 years 9 months 3 weeks 1 day 4 hours ago) and read 2617 times:

From my experience with this exact type: Yes

User currently offlineHAWK21M From India, joined Jan 2001, 31667 posts, RR: 56
Reply 5, posted (8 years 9 months 3 weeks 1 day 1 hour ago) and read 2596 times:

http://rds.yahoo.com/S=96062883/K=flame+holders/v=2/SID=w/l=IVS/SIG=11mok292n/EXP=1131078262/*-http%3A//www.fb-111a.net/OJT6-14.jpg
http://www.laugle.com/J57%20Flame%20Holders.jpg
regds
MEL



Think of the brighter side!
User currently offlineLehpron From United States of America, joined Jul 2001, 7028 posts, RR: 21
Reply 6, posted (8 years 9 months 2 weeks 4 days 11 hours ago) and read 2457 times:

From all those who described, from my point of view, I see two things:

The flow just aft of the injector and prior to the flame holder looks like it would slow to zero just before flowing to either side of the ring. Is there much stagnation from the injector to the ring itself? Would that pressure increase help the burn?

I would probably see a localized reverse flow behind the ring that is 'U' or 'V' shaped like a twin local vortex solenoid spool, so to speak. Not that there is a vacuum on the back side, but wouldn't the pressures be significantly lower to cause this flow disturbance?



The meaning of life is curiosity; we were put on this planet to explore opportunities.
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