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Why are cannular type burners used in aircraft engines if annular type have more advantages over it?

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    $\begingroup$ I'm not aware of any modern jet engine design that uses cannular combustors. Can you give some examples? $\endgroup$ – OSUZorba May 19 '16 at 14:46
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    $\begingroup$ @TomMcW - The J79 is from 1955 and the JT8D from 1960 - I'd be hard pressed to call those "modern". The Tay launched in 1984, and that's borderline "modern" at best. $\endgroup$ – FreeMan May 19 '16 at 16:13
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    $\begingroup$ @TomMcW Considering jet engines were first deployed in the early 1940s, they have had a life of ~70 years, so I would not consider 50 year-old engines modern. $\endgroup$ – OSUZorba May 19 '16 at 16:20
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    $\begingroup$ @TomMcW well, in that case, I'll give you a pass, but don't let it happen again! ;) $\endgroup$ – FreeMan May 19 '16 at 16:22
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    $\begingroup$ @FreeMan I'm really bad at cutting and pasting. I always end up cutting my hand or pasting my fingers together $\endgroup$ – TomMcW May 19 '16 at 16:32
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Single combustor cans are simpler to develop. To get the ignition and combustion process right in an annular combustor is quite a challenge. When the first jet engines were developed, Junkers decided for separate cans while BMW wanted to design a theoretically superior annular combustor. In the end, the troubles with the combustor meant that Junkers got their engine fielded much earlier, even though BMW had started their jet engine development before Junkers.

With today's CFD tools the annular design is not quite such a challenge any more.

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Modern jet engines do not use can or cannular combustors. GE made the switch to annular combustors by at least the J85, which had a first engine to test in the 1950s. The TF39 (1964) engine formed the basis of the CF6, which also uses an annular combustor. I don't know of any GE engine since the TF39 that did not use some form of annular combustors.

Modern Pratt and Rolls engines also use some form of annular combustors, but I am not sure when they made the switch.

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The first operational jet engine contract was awarded to GE/Allison as the J35 and was later upgraded to the J47. When I was at tech school for the J47 we were told GE was given the contract because they had steam turbines of similar size and quite literally modified the steam turbines to have cans and use jet fuel! The conversion was a no brainer for the cannulur design. I worked on the J47 in North American F86 Sabra jets and they were notorious for flame outs and hot starts.

The use of cannular in early jets was due to several factors. Some factors are...

1) Metallurgy was not advanced and it was easier to inject a cool layer of air on the inside surface of the can by multitudes of small holes. Today's advanced nickel alloys are more robust and annular design can withstand much higher heat.

2) Because the can metallurgy was poor, they burned up quickly. Replacing cans is relatively easy compared to an annular ring. If a can flames out, the rest of the engine is pretty much unaware, annualar engines need everything working correctly to keep the heat, pressure and air flow safely controlled.

3) Infrared heat was a major problem in early designs, the cans effectively blocked the rest of the combustion chamber from the infrared flame.

4) Early can igniters had lots of problems so they just had a couple cans with them and then used a flame tube between cans.

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