Questions tagged [turbine]

A set of rotating blades that extracts power from a flow. In aviation this primarily refers to the section of a gas turbine that extracts power from the combusted gases, as part of a turboshaft, turboprop, or jet engine.

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32
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5answers
12k views

Would it be viable to install a screen in front of jet intakes to prevent them from sucking in birds?

Why isn't there a protective screen with large diameter holes (approx 2') mounted in front of the jet engine intake to protect the turbine blades? This would keep larger birds and large ground debris ...
29
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6answers
68k views

How are turbine engines started?

What happens to a turbine engine from the time that a start is initiated until stable idle is achieved? What can go wrong?
39
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4answers
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Do turbine engines on multi-engine aircraft rotate in opposite directions to offset torque?

I'm not an aviator, I guess I'd call myself an enthusiast. I'm also a physics nut. I've always wondered about this but I equally worried my question posed to a commercial airline crew would land me in ...
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3answers
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Is it possible to drive a prop directly from a jet engine without a gearbox?

I'm studying turbojets, turbofans, and turboprops. I can see that, for the latter engine configuration, a gearbox is necessary so that the propeller rotates at a lower velocity than the main ...
13
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1answer
5k views

What is a “high-bypass geared turbofan,” and why is it so much more efficient?

According to the article Bombardier’s CSeries Gamble Is Facing Longer Odds, this new plane from Bombardier uses a new engine technology that will improve efficiency over its rival 737 series and A320 ...
16
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2answers
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Why are turbine blades not made out of titanium, only compressor blades?

According to this video on jet engine blades, titanium is never used for the turbine, because it "melts and burns at the temperature of the flame". Only the blades of the compressor are made of this ...
30
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3answers
15k views

Why do turbine engines take so long to spool up?

Piston engines reach full rpm within a second or two, but turbines take much longer. Why is that?
4
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1answer
2k views

Why does the LP compressor rotate in the opposite direction of the HP compressor?

Why does the LP compressor rotate in the opposite direction of the HP compressor in some multi-spool turbine engines?
21
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1answer
4k views

Can you identify this jet turbine stage?

I was just wondering if anyone could give me any info about this turbine rotating stage I picked up at a yard sale today. The stage measures 8-1/2" to the outside of the blades. The only markings I ...
19
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2answers
22k views

Why are aircraft turbine blades made of nickel alloys?

Why are aircraft turbine blades made of nickel alloys? What is the advantage of using them? Why did they replace steel alloys for turbine blades? How to overcome failure cases of turbine blades?
12
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6answers
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For an electric airplane are propellers the only option for propulsion?

This is for an electric airplane (so no fuels for combustion): Are propellers the only option? Is there a turbine-jet possible with only air intake, electrically compress, and a turbine and nozzle ...
7
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1answer
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How does the FADEC prevent compressor stall during rapidly increasing thrust demand?

My understanding is that if the demanded thrust is increased rapidly on a jet engine (for example going from nearly idle to TOGA during a go-around), the engine will likely experience a compressor ...
8
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1answer
5k views

How is the central hub / shaft casing of a two-spool jet engine assembled?

This is the usual view of a two-spool turbine engine: (From source) I don't know if shaft casing or hub are correct names, this is the external skin of the volume around the N1/N2 shafts. I can't ...
6
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1answer
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Which are typical rpm values for aeronautical turbines?

I wonder which of these has higher or lower rotational speed: turboshaft turbofan turbojet turboprop Does anybody know the typical speeds for these kind of engines?
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1answer
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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.
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5answers
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Is starting a jet engine without ground support possible?

We have had more... than... one question about jet aircraft taxiing about the airport without their jet engines running. Those address several issues such as cost vs savings and regulatory approval. ...
8
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1answer
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How does a labyrinth seal work when the engine isn't rotating?

I believe I understand how a labyrinth seal in a turbine engine works when a the engine is running. Any oil that makes it past the first part of the seal is thrown outwards due to the centrifugal ...
6
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2answers
1k views

Where can I get a high-res photo of the RAT from an A320 Airbus?

I'm working on a project regarding the hydraulics system of the A320 airbus. I can't seem to find a clear Hi-resolution image of a grounded A320 with the RAT extended out. Anyone know where I can ...
6
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1answer
1k views

How does the Pratt & Whitney F119 achieve its features?

The Wikipedia article on the Pratt & Whitney F119 that powers the F-22 says the following: The high pressure and low pressure turbines are single stage and counter-rotating, thus shortening ...
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1answer
4k views

What is 'blending' for a turbine blade?

What is the process of 'blending' that is used as part of jet engine maintenance?
5
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1answer
2k views

What are the limitations of using a single shaft between the compressor and turbine in a jet engine?

Question Background I'm studying the internal structure and components of a turbojet. I can see there is a shaft between the compressor and the turbine, so that energy is mechanically extracted from ...
2
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1answer
1k views

What is the efficiency of the turbine of a modern jet engine?

What is the turbine efficiency of a modern jet engine? Just the turbine efficiency only. What percentage of fuel energy the turbine converts into mechanical energy.
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6answers
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Why do large turbofans generally have many more LP turbine stages than HP turbine stages?

In almost every large turbofan I see, the LP turbine stages outnumber the HP turbine stages by a factor of at least 2. Here's a photo of the RR Trent 900: The Trent 900 (like most Rolls-Royce ...
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3answers
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Compressor-Turbine: Why a shaft and not kind of a “rotating drum”?

I'm studying the fundamentals of jet propulsion and its applications. I really have this next question and haven't found an answer yet: why do jets use a shaft (or more) to connect the turbine(s) to ...
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4answers
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What are the indications that your turbofan engine has “thrown a blade?”

In an airliner, such as an A380, what indications do the pilots have that an engine has thrown a fan blade? Will that always result in destruction (of the engine)?
8
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1answer
746 views

Why were rotary vane compressors never used in jet engines?

It seems like a rotary vane compressors have ideal characteristics for a jet engine. They can generate high pressure ratios (up to maybe 10-12) compared to older axial compressors and I think they can ...
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2answers
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How does ignited gas spin the turbine?

For the N1 fan and N2 compressor to move, the turbine needs to spin in an airliners engine. How does energy from the ignited gas spin this turbine? Do the blades on the turbine generate lift just like ...
10
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2answers
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How are fan and compressor discs balanced?

@curious-cat brought up an interesting question on another thread. How are the fan discs, compressor spools and turbines balanced on a jet engine. As they wear they surely get out of balance. Do they ...
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2answers
1k views

Is an engine surge classed as an engine fire?

Sometimes flames come out from the exhaust due to bearing distress or turbine blade fracture. Can such flames/fire be considered an engine fire?
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2answers
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Why do many large turbofans have a gap (of turbine blades) between the LP turbine and HP turbine?

After browsing around a while, I noticed that many...I think almost all...large turbofans have this gap between the LP turbine and HP turbine. I took some screenshots and put a red circle around the ...
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1answer
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What is the longevity and replacement schedule for turbine engine blades?

I'm trying to understand how frequently hot section turbine engine blades are changed out. Is this a calculation based on flight hours, material, engine size or maybe something else? Apologies if ...
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0answers
294 views

Is there an engine database that would include information on number of HPT blades per engine?

I am attempting to compile information on the number of high-pressure turbine blades across a wide range of turbine engines. Currently, I have only been able to find this information through brut ...
2
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1answer
146 views

Turbines in jet engines

I was reading this thread and in the answer, the person wrote "For example, the turbine blades are replaced after a set number of turbine cycles and/or after a set number of hours, which are lesser ...
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1answer
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Is low pressure compressor air used to cool turbine blades?

This photo shows LP cooling air is being used to cool turbine blades. the question is, is it possible to use LP air to cool the turbine blades? would you please guys explain why do they use LP air ...