Questions tagged [combustion]

For questions specifically about the process of burning fuel.

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36
votes
4answers
14k views

Why do gases in the combustion chamber only flow one direction to the gas turbine in a jet engine?

As far as I know from the working principle of jets engines, compressed air in the combustion chamber (or combustion canister) is mixed with fuel. The ignited mixture expands backwards to turn the ...
13
votes
1answer
3k views

How does a turbofan with afterburner continue to function in extreme humidity and rain?

From what I understand, the fan(s) collect(s) and compress(es) air into the compression chambers, where fuel is added to the air & combusted to create an even bigger pressure/thrust, right before ...
7
votes
3answers
677 views

Why would a jet engine use cannular combustors if the annular design is superior?

Why are cannular type burners used in aircraft engines if annular type have more advantages over it?
7
votes
1answer
1k views

How is flame stabilisation carried out?

How is flame stabilization done in a jet engine combustion chamber? What are the various ways of doing this? What are the challenges/ problems faced?
5
votes
4answers
4k views

How is the correct air speed for fuel combustion obtained at the inlet of the combustor? [duplicate]

Many jet aircraft travel at speed of about Mach .8 which at an altitude of 11 km represents an airspeed of about 300 kt or 150 m/s. If fuel was injected into air at this speed, the mix would just ...
5
votes
1answer
2k views

What is the temperature of the air leaving the combustion chamber of a CFM56-5C?

What is the temperature of the air leaving the combustion chamber of a CFM56-5C? I was wondering as I could only find out that the fuel burns at around 1500 Celsius but this can't be the same as the ...
5
votes
1answer
543 views

Are flame holders made of a special material other than that used in combustion chamber?

Are the flame holders made of materials which have higher friction coefficients than the combustion chamber in order to create turbulence?
4
votes
2answers
3k views

What is the absolute velocity change through compressor+burner?

I thought that the velocity going through a turbojet increased as it went through the compressor and the burner. Intuitively, if the pressure/enthalpy increases, so would the velocity, right? I came ...
4
votes
0answers
74 views

Does/Can combustion instabilities occur in SCRAM jet?

I was told that combustion occurs at Supersonic speeds in SCRAM jet. So acoustic disturbances/ pressure fluctuations can't travel into incoming jet stream. Does this avoids combustion instabilities in ...
3
votes
1answer
5k views

What is the difference between single and dual annular combustor?

CFM56 uses single annular and GEnX uses dual annular combustion chamber. somebody please explain with pics.
3
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2answers
1k views

What materials are used to make up a combustion chamber? [duplicate]

What type of materials are used to make up the different sections such as the linings of the combustion chambers in a gas turbine engine. Do these type of materials vary for the different types of gas ...
3
votes
0answers
152 views

Is the combustion process in turbofans and turboshafts different?

According to a journal paper, for a Gnome turboshaft engine, fuel-air equivalence ratio decreases as power output increases. However, for a CFM56 turbofan engine, the opposite trend is true, and ...
2
votes
2answers
2k views

What is the Fuel-Oxygen ratio for a large turbofan at cruise conditions?

What is the Fuel-Oxygen ratio (by mass) for a large turbofan at cruise conditions? In order to be concrete, I'll just pick an engine at random. I pick the GE90-115B. Okay it's not really random, it'...
1
vote
1answer
1k views

What are the differences between single and double annular combustion chambers?

The combustion chamber of a jet engine may be can type or annular type. Annular type combustion chamber can be SAC (single annular combustion chamber) or DAC (double annular combustion chamber). What ...
1
vote
1answer
95 views

What is the fuel/air ratio of the CFM56-5A1 engine (in the A320 model)?

I could find the fan-bypass ratio, which was 6:1 (on some models 5:1) but I was unable to find the fuel to air ratio used in this engine. For reference, it is a high-bypass turbofan engine.
1
vote
3answers
186 views

How would exhaust heat recovery into the combustion chamber affect the efficiency of a jet engine?

So, a jet engine basically sucks in air, heats it up and spits it out, right? The hotter the air gets, the faster the exhaust velocity and thus the more efficient (Higher specific impulse). Now my ...
1
vote
1answer
303 views

What is the air/fuel mixture ratio in a turbojet engine?

How does it relates to stoichiometry ? What are the possible extinction accidents related to air/fuel mixture ratio ?
1
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0answers
59 views

When are pressure-swirl atomizers and airblast atomizers used?

I am a little confused as to when (during T/O, cruise, etc.) and how the combined pressure-swirl atomizer and airblast atomizer is used. Lefebvre writes that "the merits of the pressure-swirl ...
0
votes
0answers
29 views

What was the first engine to utilise Can-Annular combustion system?

Im doing research on the history and development of combustion systems and cannot find the first engine to utilise the Can-Annular combustion system.
-8
votes
1answer
583 views

Can some one please explain to me the purpose of the combustion chamber? [duplicate]

Please, i need some one to explain to me the purpose of the combustion chamber in a jet engine, why do we need to burn the gases to get energy ? the compression does not suffice ?? is it possible to ...