flame arrester on a jet engine
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Fuel dumping systems have flame arresters to prevent a flame flowing back into the pipes/tanks. Fuel dumping is not generally done through engines though. (although it is possible through a shut down one)
Flame arrestor
Could be terminology used causing confusion.
If you are talking afterburner jet engines used on fighter planes the more common terminolgy that I have seen is "flame holder"
At any rate what they are used for is to keep the hottest part of the flame inside the engine where it can raise the energy /pressure of the gas before a duct area change (nozzle) that changes the energy into thrust.
If you didn't have a flame arrestor/holder than the air velocity within the engine woud carry the fuel droplets aft of the nozzles (either turbine inlet or afterburning) and you would continue your burning too far aft to be of use (nice blowtorch effects but quite inefficient)
The flame arrestor/holder is designed to create local turbulence which in turn increases residence time of the fuel within a given engine area so that you complete combustion of the fuel spray where it was intended.
well that's a start, let's see what else folks can add
Could be terminology used causing confusion.
If you are talking afterburner jet engines used on fighter planes the more common terminolgy that I have seen is "flame holder"
At any rate what they are used for is to keep the hottest part of the flame inside the engine where it can raise the energy /pressure of the gas before a duct area change (nozzle) that changes the energy into thrust.
If you didn't have a flame arrestor/holder than the air velocity within the engine woud carry the fuel droplets aft of the nozzles (either turbine inlet or afterburning) and you would continue your burning too far aft to be of use (nice blowtorch effects but quite inefficient)
The flame arrestor/holder is designed to create local turbulence which in turn increases residence time of the fuel within a given engine area so that you complete combustion of the fuel spray where it was intended.
well that's a start, let's see what else folks can add
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Upon further cognition, I AM aware of such a flame arrestor. It's in the sump vent of some engines, when said vent is via the exhaust centerbody. It's to prevent a tailpipe fire (unburned fuel through the turbine stages) from igniting a oil sump fire.
There is a photo of such a vent arrangement in this thread.
There is a photo of such a vent arrangement in this thread.
Last edited by barit1; 29th Apr 2009 at 18:47.
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OIL SUMP PHILOSOPHY
Booster discharge air is used for pressurization and cooling of the oil sumps.
The pressurization is achieved by a set of labyrinth seals, consisting of an air
seal and an oil seal. The difference of pressure between oil chamber and air
chamber causes the air to enter the oil chamber via the oil seals and therefore
prevents oil leaks. Venting of the air from the sump area is caused by the difference
of pressure between oil sump and ambient. The air is vented overboard
via centre air/oil separator, vent tube and flame arrestor.The pressurization is achieved by a set of labyrinth seals, consisting of an air
seal and an oil seal. The difference of pressure between oil chamber and air
chamber causes the air to enter the oil chamber via the oil seals and therefore
prevents oil leaks. Venting of the air from the sump area is caused by the difference
of pressure between oil sump and ambient. The air is vented overboard
rgds
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Flame arrester
Could it be that the original question really meant "heat diffusers" as used to reduce the chances of getting a SAM up the jetpipe? Remember Air Rhodesia using such devices on their Viscounts in the late 70's - early 80's.
Flame arrester
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Could it be that the original question really meant "heat diffusers" as used to reduce the chances of getting a SAM up the jetpipe? Remember Air Rhodesia using such devices on their Viscounts in the late 70's - early 80's.
--------------------------------------------------------------------------------
Could it be that the original question really meant "heat diffusers" as used to reduce the chances of getting a SAM up the jetpipe? Remember Air Rhodesia using such devices on their Viscounts in the late 70's - early 80's.
The winner is not the best answer it's the best guess at what the question really was
Now what's the chances that the guy who asked the question will actually come back and tell us whence the question and in what context?
Meanwhile the casual readers hopefully have learned something new from the myriad of answers.
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The winner is not the best answer it's the best guess at what the question really was
BTW - no matter how well I prepared to teach, I soon found the students would learn as much or more from each other, than they learned from me. The best I could do was to keep them steered in the right direction!
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Meanwhile the casual readers hopefully have learned something new from the myriad of answers.
..which is why most of us don't fuss too much over thread creep etc. Some of the twists and turns I have seen over the past few years have been utterly fascinating.
Now, the only problem is remembering a small part of what is rolled out in the forum ... Seniors' Moments take their toll, I guess.
..which is why most of us don't fuss too much over thread creep etc. Some of the twists and turns I have seen over the past few years have been utterly fascinating.
Now, the only problem is remembering a small part of what is rolled out in the forum ... Seniors' Moments take their toll, I guess.
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Meanwhile the casual readers hopefully have learned something new from the myriad of answers.
It amazes me sometimes what I learn on here and thats without having to learn to fly a plane too.
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ok,
To further clarify the question it was in a ATPL piston eng/gas turbine exam;
it was something like this " what is the purpose of a flame arrester"
the options where along the lines of; used for when fuel SG increaces due to temp getting colder
and the other 2 options something alongs the lines of pipping to the engine???
To further clarify the question it was in a ATPL piston eng/gas turbine exam;
it was something like this " what is the purpose of a flame arrester"
the options where along the lines of; used for when fuel SG increaces due to temp getting colder
and the other 2 options something alongs the lines of pipping to the engine???
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You call that clarification!!!
Thanks to the other posters I remember now that on the Spey 250 we used jet eflux to drain the combustion liner through a pipe and a little holding tank then a pipe sticking into the jet pipe. There must have been a flame arrestor in there somewhere.
At 40 am I too young to be forgeting this stuff?
Thanks to the other posters I remember now that on the Spey 250 we used jet eflux to drain the combustion liner through a pipe and a little holding tank then a pipe sticking into the jet pipe. There must have been a flame arrestor in there somewhere.
At 40 am I too young to be forgeting this stuff?
To further clarify the question it was in a ATPL piston eng/gas turbine exam;
it was something like this " what is the purpose of a flame arrester"
the options where along the lines of; used for when fuel SG increaces due to temp getting colder
and the other 2 options something alongs the lines of pipping to the engine???
it was something like this " what is the purpose of a flame arrester"
the options where along the lines of; used for when fuel SG increaces due to temp getting colder
and the other 2 options something alongs the lines of pipping to the engine???
Pick any of the answers above to explain what pipping is all about
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The above are what makes PPRUNE so special, the banter is all part of the fun. I thank God everyday that I am employed in the aviation industry even if I am only a lowly engineer. Don;t take life too seriously!!!
