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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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wake effect on downstream turbine

I want to perform fatigue analysis on downstream turbine blades, but I want to do this analysis with the aerodynamic forces caused by wake effects.Do you have a recommended solver to obtain such data? ...
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I'm having a hard time conceptualizing this statement from "The Jet Engine" by Rolls-Royce

This is taken from section 21 of Chapter 3, Compressors that discusses axial flow compressors in turbine jet engines. The more the pressure ratio of a compressor is increased the more difficult it ...
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What kind of combustor are these engines using?

I'm familiar with the wikipedia-standard can/can-annular/annular style combustors, but I've found a design that don't seem to fit into any of these categories, used in a number of engines such as the ...
ChipperCorgi's user avatar
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Turbocharged vs Turboprop cruise altitudes

I know that both turbocharged & turboprop engines offer better performance above 10,000 feet than normally aspirated piston aircraft. My question is to what degree do their optimal cruise ...
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What is the general operating temperature of Free Piston Turbine Engines?

The turbine in turbine engines can face temperatures from the combustion chamber up to 1700ºC, but I can't find any information on the operational temperature of free piston turbine engines. I'm ...
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What are the common sensors/ways that reverse thrust is measured for turbines?

I am looking for a sensor to measure reverse thrust on a small hobby turbine engine, a jetcat p100-rx. I did not find clear ways industry measures reverse thrust from previous searches online and was ...
Billy Dolan's user avatar
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2 answers
253 views

Why aren't ducted rotors used in gas turbines?

I am wondering why (for what I know) no gas turbine employs ducted enclosures for blade arrays on rotor stages. I tried to search the internet for resources but I couldn't find anything related (so I'...
temporary_pigeon's user avatar
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Why TBM 850 checklist calls for high idle during taxi

According to the TBM 850 checklist, at 13% NG you introduce LO Idle. But before taxi all TBM 850 pilots select high Idle. I was under the impression that high idle is selected for takeoff. Anybody ...
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Why do only turboprops have ground/flight idle selections?

Why is it that only turboprops have a pilot controlled flight/ground idle and not jets?
Boeing787's user avatar
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Aerofoil selection for a Horizontal turbine [duplicate]

I'm currently having a bit of an issue selecting the type of aerofoil I would want to use in my ridge mounted wind turbine honours project. I want to select a high lift generating aerofoil at low ...
Henry's user avatar
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The phase having the hightest TIT for a flight mission

I have a query concerning the turbine inlet temperature (TIT) in the context of various flight mission phases. Specifically, I'm trying to ascertain at which phase the gas turbine reaches the highest ...
mumu's user avatar
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Is there a reason for the difference in turbo prop exhaust placement?

The TBM 940 and Cessna caravan both have the PT6A turbo prop engine. The sister caravan has one single exhaust stack under the engine cowling, and almost all other small turbo props have dual exhaust ...
Boeing787's user avatar
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Do compressors and turbines in jet engines end with rotor or stator?

I am trying to understand compressor and turbine design principle based on stators and rotors. I know that turbines and compressors both have a rotating and fixed section that constitute a stage. For ...
Jawel7's user avatar
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What is the purpose of variable stator vanes in the power turbine part of a free shaft gas turbine?

both M1 Abrams tank and T-80 tanks have free shaft gas turbine engines and both of their engines have variable stator vanes in their power turbine part. It says in the picture below that these ...
Timothy Scherer's user avatar
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Why is the turbine that drives the compressor is placed before the free turbine in a gas turbine engine?

For example in the picture below we can see that the turbine of the compressor is just behind the combustion chamber and gets the hottest gas and i think therefore can extract the most energy? The ...
Timothy Scherer's user avatar
7 votes
5 answers
2k views

How do gas turbine engines and turbofan engines keep constant compressor side rpm?

How do the RPMs stay constant in a gas turbine engine? For example in car with piston engine, when you keep pressing the accelerator the rpms keep picking up, to keep the rpms constant you must let ...
Timothy Scherer's user avatar
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2 answers
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Will all turbine blades stop moving in the event of a emergency shutdown?

In the event of an emergency shutdown of an engine (while in the air), are there systems which prevent movement of turbines (brakes) in case of internal damage? Or will that cause aerodynamic drag ...
Brendan's user avatar
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Why do turbine rotors have an outer shroud but compressors don't?

I know it's purpose is to prevent interstage leakage of pressurised gases, but then shouldn't the compressor stages have it as well? Why is it exclusive to the turbine stages?
Aditya Sharma's user avatar
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What is the amount of bleed air required for de-icing? What is the power impact of this bleed air?

I was wondering if anybody has any rough equations/figures that answer the following questions. What is the mass/flow rate of bleed air required for de-icing based on temperature of the air intake? ...
Liam's user avatar
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9 votes
3 answers
5k views

What originally spins the intake fan when the engine is started?

I've been thinking about doing a presentation about how jet engines work. I've watched some videos and everything seems understandable to me, but I have one question. What originally starts spinning ...
doorenjoyer's user avatar
1 vote
2 answers
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What happens when you put significant weight on the tail of a commercial airplane?

I'm curious what happens if you put some extra weight in the back of the airplane (let's say a small GE turbine or something). I'm new to Stability and Control side of things and curious how the new ...
Jones's user avatar
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Poor airfoil choice for wind turbine

I am getting involved in an outreach project where I can modify a small wind turbine with different wing geometries. Are there examples of standard airfoil designs with particularly poor Cl/Cd ...
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1 answer
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Why does the gas turbine recuperator hugely increase efficiency but slightly decrease the peak power?

I understand that the heated intake air will burn more efficiently with the fuel and that's why recuperators increase efficiency. The part I don't understand is that if efficiency is going up, why isn'...
Timothy Scherer's user avatar
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Safran 2S2 Engine Overhaul

Does overhaul of Safran 2S2 Engine reset all engine inspections? If engine TSO is 0 as of today, does it mean I can reset all 15/20/30/300/600/3000/3500 hours inspection to be 0? Or I have to see Shop ...
Bipin Patel's user avatar
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1 answer
315 views

How can an N1 speed change and an N2 remain the same?

In reference to a rotorcraft turbine engine (turboshaft): "How can a power turbine rotor speed N2 (or Npt) and rotorcraft rotor speed Nr both be at 100 % while the gas generator speed N1 (or Ngg) ...
Wes's user avatar
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1 answer
748 views

Why does the torque curve of free shaft gas turbines keep gradually dropping as RPMs increase?

When i look at the output shaft torque curve of a free shaft gas turbine i can see that they are almost like an electric motor. It makes peak torque at very low rpm and then torque keeps gradually ...
Timothy Scherer's user avatar
3 votes
2 answers
2k views

How a power assurance check works?

In a Bell 407 the power assurance check takes into account torque, pressure altitude and MGT (measured gas temperature aka TOT). The flight manual states that if MGT when tested is less than or equal ...
Wes's user avatar
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8 votes
2 answers
2k views

How exactly is the free shaft part of a gas turbines controlled?

As you can see in the picture, the free turbine still gets the same exhaust gas that the main turbine gets. How can it exactly spin freely from the main turbine? How can the free shaft even stay ...
Timothy Scherer's user avatar
2 votes
2 answers
1k views

Would a pulsejet/turbine hybrid be efficient?

A pulsejet is an engine with a few moving parts (only the chamber shutters I think) in which fuel is injected in the combustion chamber, leading to a explosion that pushes air to the exhaust. After ...
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Turbine engine part identification

I picked this up at a yard sale (we call them boot fairs in the UK) Can anyone identify it ? I'm not good with gas turbines. It is stamped with the serial number 579451A. Its 40 inches in diameter, ...
Simon Collins's user avatar
5 votes
2 answers
1k views

How much water does it take to cause a flameout in a modern turbine engine?

Turbine engines such as the PT6 that have inertial separators have a reputation for being able to deal with intake water very well. How much can they handle? Do the manufacturers torture-test their ...
Ryan Mortensen's user avatar
12 votes
2 answers
3k views

What does the small needle + scale on this turboprop's N1 gauges indicate?

Look at these weird turboprop N1 gauges: I'm referring to the smaller needle at the top of each PERCENT RPM labelled N1 gauge. What does it display ? I have no ...
TheEagle's user avatar
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3 votes
3 answers
860 views

What causes ram air turbines with more blades to spin slower than turbines with two blades? [closed]

Lets say aircraft has two ram air turbines that work as generators to produce electricity on each wing. One has two blades and one has 8 blades, both with the same diameter. What is the aerodynamic ...
22flower's user avatar
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6 votes
7 answers
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Are there Hybrid Electric-Combustion Turbine Engines where only the compressor is electric driven?

So, from what I could understand about conventional Turbine Engines and its various types is that normally the combustion chamber ignites fuel with compressed air, rotating a low pressure fan which ...
mandiokai's user avatar
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0 votes
1 answer
194 views

Can a fixed pitch propeller be designed to act as both a propeller and a generator?

The angle of attack (AoA) plays a major role in designing a propeller for specific uses, such as if it is to be designed for aircraft propulsion the AoA must be high, while the AoA must be low if it ...
Mohammed Siddique's user avatar
3 votes
5 answers
4k views

Would it be possible to put wind turbines alongside runways that are driven by the exhaust of planes?

The only thing somewhat similar that I could find is research from students to use air vents from factories. This is of course a much lower force to deal with. I'm curious if someone could give some ...
Max's user avatar
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2 votes
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There is any example/studies/concepts on really short blade jet turbines/turboshafts? [closed]

Well, from the little I know, I think the reason jet turbines can't go that fast is because the tip of the blades would reach supersonic speeds and starting to generate too much drag. However, if, for ...
Fulano's user avatar
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3 votes
0 answers
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How does the pressure distribution at the blades of a radial turbocharger look like?

Consider a piston engine equipped with a turbocharger. In the turbine section of the turbocharger, the pressurized exhaust airflow comes from the center (radially) to the blades, then changes ...
22flower's user avatar
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2 votes
2 answers
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What type of bearings are used to support the shafts in jet engines? [duplicate]

I would like to know which types of bearings are commonly used to support the shafts in jet engines and why. I also read something about hydrodynamic bearings, how common are they?
woj812's user avatar
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4 votes
2 answers
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Are turbine blisks common in jet engines?

This comes from a slightly related question about blisks. A blisk is a single component shaped like a disc with blades on it. This can be for compressors or turbines. I want to ask about the turbine ...
DrZ214's user avatar
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12 votes
3 answers
3k views

Is the compressor required on jet engines? Can air be rammed into the turbine?

In the context of a common airliner (say Boeing 777), when the airplane is on the ground, and the turbines are on, air is getting sucked in and compressed/bypassed. The engine has to do work to ...
user59993's user avatar
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7 votes
1 answer
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Why is turbine inlet temperature called "TET"?

I assume that at some point giggling engineering students caused their instructor to change "turbine inlet temperature" from TIT to TET, but I wonder if anyone knows the real reason and ...
Maury Markowitz's user avatar
2 votes
1 answer
187 views

Can a hybrid electric turboprop reduce fuel consumption 30% on regional flights?

UTC has a hybrid electric research project called Project 804, in which it claims that augmenting takeoff turbine power with electric power allows a smaller turbine for cruise, thus saving 30% of fuel ...
Pilothead's user avatar
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3 votes
2 answers
974 views

In a jet engine, what is the significance of the stagnation pressure/temperature?

I'm reading a paper on jet engines that repeatedly mentions the stagnation pressure and temperature. What does this mean? Is it the point where the jet engine stalls in performance/efficiency/thrust, ...
itisyeetimetoday's user avatar
2 votes
1 answer
2k views

Do turbine and compressor rotate in opposite direction?

I have heard that they do rotate in opposite directions to maintain the equilibrium of the engine. That is the net force generated by the rotation is nearly equal to zero. But, I don't think the ...
Auberron's user avatar
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11 votes
2 answers
1k views

How often is the fuel sampled in turbine aircraft?

In planes using avgas, sampling fuel from the tanks is generally done before every flight, or at least before the first flight of the day and then after any refueling. This is done because water ...
Jan Hudec's user avatar
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2 votes
3 answers
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What other materials apart from conventional nickel and steel superalloys can be used as a first stage turbine blade material?

Steel and nickel chromium alloys have been prominent and most used as turbine blade material although there are other materials such as tantalum carbides, tungsten and many more which I have no ...
Walter White's user avatar
1 vote
1 answer
2k views

What is the difference between RTOP, MTOP, and MCP?

I am currently learning how to fly the SD3-60 (Shorts) Aircraft, and I am trying to gain an understanding of RTOP (reserved take off power), MTOP (max take off power), and MCP (max continuous power). ...
Rose P.'s user avatar
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Does Betz's Law apply to jet engine turbines?

Betz's Law says the extractable power from wind is only 59% (16/27) of its original power. $$P_{max} = \frac{16}{27} \frac{1}{2} \rho A v^3$$ Rho is the gas density, A is the cross section area of gas ...
DrZ214's user avatar
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5 votes
2 answers
2k views

Has there ever been a centrifugal turbine in an aircraft engine?

These days, most jet engines feature axial compressors and turbines. However, there are some older aircraft engines with centrifugal compressors, like the Rolls Royce Nene. But I've never heard of any ...
DrZ214's user avatar
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