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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39
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4answers
19k views

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 ...
32
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5answers
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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 ...
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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?
29
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6answers
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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?
21
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1answer
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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 ...
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2answers
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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?
18
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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 ...
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 ...
15
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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 ...
14
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1answer
2k views

What are these engine inlet devices used for?

While looking at the Boeing Chinook CH-47 for this question, I noticed the screens in front of the engines, and found similar devices in other photos: Source: left -- right What are these devices ...
13
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5answers
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Has anyone burned hydrogen in a turbine?

I am just wondering if supplying compressed hydrogen to a turbine would be a better fuel as it has three times the octane rating of kerosene. It just seems better all around.
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2answers
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What engine are these fan blades from?

I bought these from a metal scrapper and paid about $30.00 total figuring they're worth more than that in cool factor. Problem is they aren't nearly as cool if I can't figure out what engine (and ...
13
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1answer
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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 ...
12
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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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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 ...
11
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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. ...
11
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4answers
3k views

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)?
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At what point is a turbine powered ducted propeller considered a turbofan?

Turboprop Propellers can be ducted for extra thrust. What are the criteria for determining that the engine is no longer a ducted propeller design, but a turbofan? Does there have to be a type of ...
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 ...
9
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2answers
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Why can't we extract more from exhaust gases in gas turbines?

It is seen that EGT are of the order of 600°C (What is a normal EGT range of a jet engine?) for aviation turbines and nearly the same for stationary turbines. Why can't high temperature exhaust gases ...
9
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3answers
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is boundary-layer jet-turbine a scam?

While exploring open jet turbine designs, I've stumbled upon one CAD drawing which has made me wonder. It is based on a famous Tesla turbine and its highly-efficient way of compressing the fluid. At ...
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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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If jet engines did leave chemtrails, wouldn't the chemicals cause adverse reactions in the engines?

Please note, this question does not call into question whether or not the conspiracy theory is true or untrue, but the feasibility of certain chemicals being used as fuel additives in order to make ...
9
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1answer
750 views

What to do when pneumatic air cycle kit stops working mid-flight on Boeing 737-800?

If you are flying a B738 at FL390, and one PACK (pneumatic air cycle kit) becomes inoperable, do you have to descend to FL250? If so, do you need to divert for fuel?
8
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1answer
448 views

What's that rattling noise from parked jets? [duplicate]

While walking around the airport on a windy day I occasionally hear a tingling or rattling noise from the engines of the parked jets. You can see the fans rotating in the breeze. What’s causing the ...
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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 ...
8
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1answer
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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 ...
8
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1answer
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What is the visual difference between turbine fans and compressor fans?

How to identify that a given fan is a compressor fan or a turbine fan, just by visual inspection? Also, can visual inspection of a fan help in identifying the compressor/turbine stage i.e. if the fan ...
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 ...
8
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1answer
6k views

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 ...
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3answers
640 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
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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 ...
7
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2answers
722 views

Are turbine engine reconditioned after severe FOD damage caused by bird strikes?

I've just been watching a video of a 757 suffering a bird strike on take off. The pilots continue with their take off, declare a MAYDAY, shut the engine down and proceed to land without any issues. ...
7
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3answers
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Can a GA magneto-spark plug ignition survive an EMP?

Can the coil and capacitor (condenser) magneto/spark plug ignition system as exists on most general aviation aircraft survive an EMP? Let's talk about a standard Lycoming or Continental engine. How ...
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
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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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Why is the A400M APU on the side of the fuselage instead of the back?

As you can see in this picture the APU of the A400M is on the side under the right wing, including the RAM-Air-Turbine. Why is the A400M APU on the side of the fuselage instead of the back? Why is ...
6
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1answer
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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
318 views

Where is fuel metered in continuous flow fuel injection system?

How is fuel metered in continuous flow fuel injection system?
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1answer
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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
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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 ...
5
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1answer
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Why aren’t diesel piston engines used on aircraft like the Saab 340 or L-410?

In contrast to this question (link), I would like to know the opposite - why diesel piston engines aren't used on aircraft with comparable role and configuration to Saab 340, L-410, ATR-42? There's ...
5
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1answer
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What is the equation for the energy balance between turbine, compressor and propeller?

Let's consider the next turboprop arrangement: What I am looking for I am looking for an equation that involves $\dot{W}_T$, $\dot{W}_C$ and $\dot{W}_P$ (i.e. the power done by each component). This ...
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1answer
140 views

Time Tracking: Does Turboshaft count towards Turbine time?

another edit To clarify - I'm programming an application for logbook tracking and want to automate turbine time calculations to help people fill in insurance firms easily. edit: I guess a more ...
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1answer
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What is the effect of power extraction on turbofan compressor and turbine maps?

Effects of Power Extraction on Turbofan Compressor and Turbine Maps The two diagrams below show the effects of shaft power extraction (shaft power offtake / shaft power off-take for the propulsion of ...
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3answers
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What are the major hazards in operating a PT6 Turbine Engine?

I am just in the process of doing a bit of study in the hope of doing my Basic Gas Turbine Endorsement in the next few months, and just wanted some feedback/comments/discussion on the major hazards ...
4
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1answer
763 views

Is this a blisk?

GE Aviation bought the Czech company Walther to get their 600-800shp turboprop engines, now called the H75... On their website, two thirds down the page, the following picture has the caption The H-...
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2answers
436 views

Is my understanding of a gas turbine engine compressor correct?

So I understand that the rotors add dynamic pressure to the airflow and this dynamic pressure airflow is transformed into static pressure in the stator vanes. But now does the airflow still have ...
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2answers
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What turbine blade alloy did the Jendrassik Cs-1 use?

Wikipedia says that the first turboprop aircraft engine was the Jendrassik Cs-1 invented in Hungary by György Jendrassik. It says it was supposed to run at 1000 hp but "combustion problems" limited ...
4
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1answer
1k views

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 ...