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.
154
questions
1
vote
1
answer
369
views
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 ...
- 263
1
vote
2
answers
89
views
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 ...
- 263
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 ...
- 263
10
votes
2
answers
3k
views
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 ...
- 109
1
vote
1
answer
192
views
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?
- 2,132
0
votes
0
answers
69
views
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?
...
- 1
9
votes
3
answers
4k
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 ...
- 93
1
vote
2
answers
137
views
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 ...
- 11
5
votes
1
answer
244
views
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 ...
- 153
1
vote
1
answer
240
views
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'...
- 149
0
votes
0
answers
47
views
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 ...
0
votes
1
answer
222
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) ...
- 459
3
votes
1
answer
278
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 ...
- 149
3
votes
2
answers
525
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 ...
- 459
7
votes
2
answers
1k
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 ...
- 149
2
votes
2
answers
363
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 ...
- 542
3
votes
0
answers
163
views
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, ...
5
votes
2
answers
568
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 ...
- 8,681
11
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 ...
- 1,158
3
votes
3
answers
779
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 ...
- 1,563
4
votes
6
answers
2k
views
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 ...
- 542
0
votes
1
answer
176
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 ...
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 ...
- 47
2
votes
0
answers
79
views
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 ...
- 137
3
votes
0
answers
92
views
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 ...
- 1,563
2
votes
2
answers
2k
views
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?
- 21
4
votes
2
answers
534
views
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 ...
- 17.4k
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 ...
- 131
7
votes
1
answer
1k
views
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 ...
- 1,456
2
votes
1
answer
166
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 ...
- 18k
3
votes
2
answers
495
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, ...
- 225
2
votes
1
answer
754
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 ...
- 1,537
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 ...
- 55.5k
2
votes
3
answers
102
views
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 ...
- 21
1
vote
1
answer
908
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). ...
- 11
1
vote
0
answers
216
views
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 ...
- 17.4k
4
votes
2
answers
837
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 ...
- 17.4k
2
votes
0
answers
141
views
Why does the LEAP 1A HPT run at such a high RPM?
I've watched the N2 on the LEAP sit at 100% at cruise and fluctuate as high as 101%. Why does the HPT run at such a high RPM?
- 21
2
votes
2
answers
130
views
What do these temperature data listed in the EASA Type Certificate Data Sheet mean?
Could you tell me what is the Maximum Permissible Indicated Turbine Temperature (ITT) and the ambient limit temperature for sea level static thrust?
- 313
0
votes
1
answer
142
views
What gas turbines have the following configuration?
Is there any jet engines--with published data on the dimension of the turbines and compressors--that are of the configuration of 2 Low Pressure compressor, 8 High Pressure compressor, 2 High Pressure ...
- 313
0
votes
0
answers
52
views
What is the diameter of each stage of the PW800 engine compressor and turbine?
I am an Aerospace Engineering student working to analyze P&WC's PW800 engine family--specifically, the PW814GA, for a project and we need to know some hard-to-find data.
Does anyone knows where I ...
- 313
0
votes
1
answer
112
views
Why is tangential velocity a loss of kinetic energy in a turbine section?
While researching turbine engines I came across a statement
The mass of airflow naturally does not change in the transfer of energy to the rotor system, but the velocity of mass flow being slowed ...
- 601
1
vote
1
answer
264
views
What is the temperature range of engine mounts connected to the pylon?
I want to know what is the temperature of the engine mounts in modern turbofan engines for example, Rolls Royce Trent 900. Also, what are the temperature considerations you need to make while ...
- 41
1
vote
6
answers
331
views
Would a piston or turbine engine be best suited for a small UAV flying 8000miles?
I am trying to devise a concept that would airdrop medical supplies around remote regions of Africa: vaccines, medicine, blood... etc. I image the payload would be anywhere between 1-2 ton. I think a ...
- 59
1
vote
1
answer
3k
views
How to find the static stall angle of attack for a given airfoil at given Re?
For vertical axis wind turbines applications
I'm wondering how one would find the static stall angle of an airfoil at a given Reynold number?
Is it just the critical angle of attach (AoA) where ...
- 111
5
votes
0
answers
282
views
How did the Blackops 'quiet one' helicopter muffler work?
Back in the Vietnam War era, special ops needed a quiet means of inserting soldiers behind enemy lines to install eavesdropping equipment. They modified a Hughes 500 to do the job. One of the things ...
- 18k
0
votes
0
answers
43
views
How is fuel ignited in jet engines? [duplicate]
From what I understand, in jet engines, air is compressed and fuel is not only injected but also ignited : how is this done ?
- 11
6
votes
3
answers
503
views
Turbofan engine start - Why does ignition occur so early?
In another thread, two key steps of starting a turbofan (ignition and fuel introduction) are given as follows:
With increased N2 rotation, ignition will be turned on. [...]
With further ...
- 63
13
votes
3
answers
9k
views
How hot do internal parts of jet engine get?
How hot does a jet engine get? I'm interested in the temperature of the parts, not of the exhaust or combustion. If you took temperature of an engine after a flight across the Pacific Ocean what are ...
- 139
2
votes
1
answer
99
views
Could high density abrasion-resistant ceramic turbine blades allow for the use of borane fuels?
In the late 1950s the U.S Air Force searched for a fuel with similar characteristics to jet fuel but with higher energy density allowing longer flight range for bombers. In 1947 the British had ...