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Hi Guys,

I noticed recently that flame colour of afterburner of the F100 -229 model is quite different than the older F100 -220/E model. The older one have dusk-orange ab flame, while the -229 have ligt blue/yellow colour.
Could somebody explain the reason(s) for such difference in the ab's flame colour between this two engines ?

To illustrate (F-15):

-220:

-229:

O btw, what makes that circle rings into the pillar of burner flame ? Sound wave or smomething...?

Thanks for help Smile

.

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Elite 1K Joined: May 26, 2005 Posts: 1134

They're called mach discs. http://www.aerospaceweb.org/question/propulsion/q0224.shtml

As to the color difference, my guess would be different exhaust gas temperatures (higher temperature = more blue)?

Gus has it exactly. Cheers

Exhaust gas velocity makes the rings/disks. They are shock waves in the exhaust.

As for the color, it's the exhaust gas' temperature.

Just like any flame, blue is hotter than yellow or orange.

The PW-229 has a much more efficient augmentor than the PW-220. Twisted Evil

Great observation Patriot!

I can't wait to see the T-Birds in 2009 with their PW-229 powered Blk52s! Cool

Elite 1K Joined: Jul 22, 2005 Posts: 1012 Status: Offline

That_Engine_Guy wrote:

Gus has it exactly. Cheers

Exhaust gas velocity makes the rings/disks. They are shock waves in the exhaust.

As for the color, it's the exhaust gas' temperature.

Just like any flame, blue is hotter than yellow or orange.

The PW-229 has a much more efficient augmentor than the PW-220. Twisted Evil

Great observation Patriot!

I can't wait to see the T-Birds in 2009 with their PW-229 powered Blk52s! Cool

The thing I don't get is why one time an engine's exhaust might appear blue and others orange. I've seen B-1's in afterburner both with blue and orange, pictures of both the F100-232 and F135 on the test stand with almost violet flames yet the F135's flame is orange most of the time when you see it in the aircraft. Shrug

You'll get some variance based on atmospheric conditions as air density affects the engine's ability to create thrust to some degree.

Some older engines will also loose efficiency due to deterioration of the the engine and/or deposits in their augmentor fuel systems. (PW-220s require the augmentor spray manifolds to be baked to remove carbon deposits on a scheduled basis.) This will cause the color of the flame to vary between engines of the same type.

The angle at which you view the flame and the background color will affect the flame's visibility to your eye or camera as well.

On a sunny day in a nice blue sky it is very difficult to see the blue components of a PW-229's flame, only the yellow portions can be seen. Take that very same aircraft/engine into the test cell, with limited lighting, and steel interior walls and the blue becomes very evident... Devil

Newbie Joined: Sep 17, 2006 Posts: 8 Status: Offline

I wonder when & where did you notice it Patriot (eNwings) Very Happy

Enthusiast Joined: Apr 10, 2007 Posts: 73 Status: Offline

You never mentioned if the fule was running with the new additive requirements of 100.

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P&W 220/E and 229 - AB flame colour