Afterburning thrust augmenter?

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James D
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Afterburning thrust augmenter?

Post by James D » Mon Oct 31, 2005 9:20 pm

I was looking through some old SNECMA patents and found reference to an afterburning thrust augmenter.
Has anyone tried it?

Quote from patent
"...... it is possible to obtain a substantial increase in the performance, as regards thrust, by introducing additional fuel by means of an injector 16 in the 85 interior space of the cowling member 1a, on the downstream side of the smallest transverse section of this member The chamber 13 is the seat of an extremely turbulent periodic flow and the combustion 90 takes place in this chamber with an excellent stability In this alternative form, also, it is desirable that at least the members 3 and 13 should be of refractory material......"
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SNECMA Patent 1955
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re: Afterburning thrust augmenter?

Post by Mike Everman » Mon Oct 31, 2005 10:22 pm

That's the AS-1 again. I wondered why the augmentor was so long!

Any other afterburners I've seen have been little more than lightshow/fuel burners, based on the more standard short augmentors.
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Bruno Ogorelec
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re: Afterburning thrust augmenter?

Post by Bruno Ogorelec » Tue Nov 01, 2005 10:05 am

What I have never been able to determine is the nature of the events in such an afterburner. Namely, is it an afterburner or an after-pulse-burner?

If it is an afterburner, what lets it maintain combustion? Why isn't the flame blown out of the duct?

If it is another pulsejet, in sequence with the first, the question is (again) what makes the mixture slow down in order to to ignite?

What provides ignition? The flame from the engine proper almost certainly cannot do it -- by the time the combustible mixture in the afterburner has formed, the hot gas flow incoming from the front engine is almost certainly too cool and diluted to serve.

Lots of questions.

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re: Afterburning thrust augmenter?

Post by leo » Tue Nov 01, 2005 7:54 pm

James what’s the patent number?.

Looks interesting, maybe we can make the thrust augmenter work like a ramjet complete with flame holders and injection, feed with air by the pulsejet

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re: Afterburning thrust augmenter?

Post by James D » Tue Nov 01, 2005 9:41 pm

The number is GB786232

& link to the patent,
http://v3.espacenet.com/textdoc?DB=EPOD ... N=GB786232
However most of the application^ just refers to the cowling around the pulsejet.

Another Drawing on the same patent seems to show an internal baffle in the combustion chamber of the pulsejet, But its not mentioned in the text. I wonder if its in another document ?
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Internal geometry?
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Jonny69
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re: Afterburning thrust augmenter?

Post by Jonny69 » Wed Nov 02, 2005 12:58 pm

I've got a couple of patents with internal baffles like that. They seem to be there to reduce the backflow through the intake.

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re: Afterburning thrust augmenter?

Post by leo » Wed Nov 02, 2005 9:39 pm

In the aviolanda AT-21 the used the AS-11 with 70 kg off thrust, but it was possible to fit a other engine called the AS-21, this engine supposed to be off the same size but with more trust, maybe this was a engine with the afterburner installed.
See the pictures of this drone in this topic.
http://www.pulse-jets.com/phpbb2/viewtopic.php?t=2361
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serverlan
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re: Afterburning thrust augmenter?

Post by serverlan » Thu Nov 03, 2005 1:01 pm

Could that extra baffle be a flame holder?

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re: Afterburning thrust augmenter?

Post by serverlan » Thu Nov 03, 2005 1:10 pm

Hey Bruno,

I think of the concept of sort of a hybrid pulse/ram stye augmenter
(at least thats my idea. not sure about the provided diagrams.)

The augmentor runs a bit like a Ramjet.
Stationary, it can only work when a pulst of pressure /flow arrives from the pulsejet. would need some form of flameholder in the meantime.

When moving, an augmenter could be designed that scoops in air from the movement (wider mouth than those shown. A funnel shaped mouth would also help to concentrate the pressure wave from the pulsejet).
At moderate speeds, the augmenter would only run efficiently with the pulses arriving from the pulsejet.
As it gets faster, its onw ramjet efficiency increases, with the pulsejet providing peaks of high efficiency.
Eventually the pulsejet becomes insignificant.

Don

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re: Afterburning thrust augmenter?

Post by Mike Everman » Thu Nov 03, 2005 3:57 pm

I think that's close. So you have alternating plugs of hot and fresh gas going through. As a ramjet analogy, you wouldn't need a flame holder, the fresh air and fuel plug will touch off when the mix is right, initiated from ahead and behind. Very cool. Gotta suck some fuel, though!

Nice animation, Leo, can you zip it up, I can only copy one frame.
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re: Afterburning thrust augmenter?

Post by leo » Thu Nov 03, 2005 7:27 pm

Mike if you save it directly to disk it works fine.
Don’t copy it.
I have a bigger gif if you want it, this one is only 40% size.

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re: Afterburning thrust augmenter?

Post by Mike Everman » Thu Nov 03, 2005 7:34 pm

Oh, I did that, I just realized I needed to view it with a browser. Thanks.
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