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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2 answers
578 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 ...
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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 ...
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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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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'...
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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 ...
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1 answer
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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) ...
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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 ...
3 votes
2 answers
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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 ...
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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 ...
2 votes
2 answers
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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, ...
4 votes
2 answers
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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 ...
11 votes
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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 ...
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3 votes
3 answers
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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 ...
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5 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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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?
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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 ...
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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 ...
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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 ...
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1 answer
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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 ...
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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, ...
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1 answer
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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 ...
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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 ...
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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 ...
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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). ...
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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 ...
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2 answers
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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 ...
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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?
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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?
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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 ...
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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 ...
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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 ...
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1 answer
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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 ...
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6 answers
323 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 ...
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1 answer
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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 ...
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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 ...
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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 ?
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3 answers
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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 ...
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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 ...
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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 ...
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Has anyone burned hydrogen in a gas turbine?

I am just wondering if supplying compressed hydrogen to a gas turbine (combustor) 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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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 ...
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How do the contrarotating turbines work in the F-119-PW-100?

I was reading about the F22 Raptor and found out that its powerplants use contrarotating turbines. How does this work Also, if the spools and their connected compressors are rotating in opposite ...
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1 answer
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How can I calculate turbofan efficiency as a function of turbine inlet temperature?

I know that increasing the turbine inlet temperature (TIT) increases the overall efficiency of the jet engine. So I wanted to find the overall efficiency as a function of TIT. I used the equations ...
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1 answer
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Turbine blade manufacturing/assembly process

I want to know the process for manufacturing turbine blades and the companies that are involved. Who makes the turbine blades? Who applies the thermal barrier coating? Who repairs the blades? Let's ...
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Do the compressors and turbine rotate at the same speed?

Since the turbine and the compressors are connected to each other via a common shaft, do they both rotate at the same speed. Because I've read that in some jet engines (single spool engines) they don'...
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