Pressure gain combustion ?'s

Jets that defy normal classification

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luc
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Re: Pressure gain combustion ?'s

Post by luc » Wed Nov 05, 2008 2:05 pm

No. 44 wrote:You know, I've taken a peak at some of the first gas turbine engines and it seems that one of the original attempts by Frank Whittle involved placing several small combustion chambers around the compressor/turbine. The compressor would force air into the combustion chambers and the exhaust would be recombined at the end when turning the turbine and exiting the assembly. Maybe Zippiot was onto something by placing several pulsejets around a super-sized turbocharger.
Yeap ... We call that a "Can annular" combustion chamber concept. One of the aircraft that use to have such engines was the famous F-4 Phantom in its early stage, but I think it was later upgraded with "Reverse Annular" chamber engine later on ... But don't quote me on this last one, but I am quit certain with the previous.

One of the major reasons and/or advantage of a "Can Annular" concept, is that individual chambers are easyly replaced if damaged or cracked occures instead of splitting the engine in aft for changing the entire chamber. But again, I think this is also the reason why the Phantom was also know as the "Smoker" for this perticular engine concept was know to leave a trail of smoke behind, which is not that good when trying to avoid detection in a war scenario. Actually, the never knew and found out why this engine was smoking that mutch and talking to an EX Phantom engine mechanics years ago ... Lolllllll.

But I personally see this concept coming back, especially with the outcomes of better Pulse-Jets and PDE engines for I lately read that there are few new projets involving Pulse-jets and PDE engines on NASA tables. But you will need to check this one out.

Regards,
Luc
Designer & Inventor

Zippiot
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Re: Pressure gain combustion ?'s

Post by Zippiot » Mon Nov 10, 2008 7:43 am

Just been thinking and playing around in the garage....
At what point is induced flow "bad" for a pj? Partial chokes could be setup to restrict the high-speed/flow of air so the pj continues to run at a good pace but the turbine is allowed to do as it wishes even if thats just push air through that doesnt get combusted. Afterall thats what a turbofan does right?
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No. 44
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Re: Pressure gain combustion ?'s

Post by No. 44 » Tue Nov 11, 2008 11:18 pm

Zippiot wrote:Just been thinking and playing around in the garage....
At what point is induced flow "bad" for a pj?
Interesting question, am I correct in assuming you're afraid that with too much air being force in it will stop acting like a pulsejet and more like a conventional combustion chamber?
Partial chokes could be setup to restrict the high-speed/flow of air so the pj continues to run at a good pace but the turbine is allowed to do as it wishes even if thats just push air through that doesnt get combusted. Afterall thats what a turbofan does right?
Turbofans come in many configurations but they all direct at least some incoming air around the engine. In an engine with multiple PJs placed around what would essentially be a giant turbocharger it might be problematic to try directing air around the central bulk, what with already increased frontal area.

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