Questions tagged [compressor]

As the name suggests, gas turbine engine compressors provide the compression part of the gas turbine engine thermodynamic cycle. There are three basic categories of gas turbine engine compressor: axial compressor, centrifugal compressor, and mixed-flow compressor. A fourth, unusual, type is the free-piston gas generator, which combines the functions of compressor and combustion chamber in one unit.

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How does the Allison (now Rolls-Royce) CX-31 centrifugal compressor achieve a pressure ratio of 10?

Centrifugal compressors typically have pressure ratios up to around 7 or 8. But Rolls-Royce has a graphic showing the evolution of their line of small turboshaft engines that shows the compressors ...
sf44's user avatar
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Function of the compressor in a gas turbine engine

I am trying to understand the importance of having compressed air in the combustion chamber of a gas turbine engine. As far as I understand it, the reasons are twofold. Firstly, the compressor is ...
bchen's user avatar
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Decreasing Area of Axial Compressor

in axial compressor, why the area is decreasing until it reaches the combustor? and if the answer because of the pressure is inversely proportional to the volume. that's happened when the temperature ...
Nagy Ashraf's user avatar
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1 answer
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Why do we take into consideration holes for pressure thrust in jet engine calculations?

In many sources related to jet engine thrust calculations such as https://www.jet-x.org/a8.html , pressure thrust of a module such as combustion chamber, nozzle or compressor, is calculated by front ...
Jawel7's user avatar
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How can flow in the compressor of a jet engine go back to the inlet?

In aerodynamic lessons and books about jet engines, it is always said that there is a risk that air flow in the combustion chamber or compressor can go back to reverse direction, towards the inlet if ...
Jawel7's user avatar
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Why do we consider that air comes into jet engine?

While calculating air pressure and temperature during cruise of jet engines, we consider that air comes into the jet engine inlet with our flight velocity. But why? In fact, air stops stagnant in ...
Jawel7's user avatar
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What increases the rotational velocity of air in an axial flow compressor?

In an axial flow compressor as used in modern jet engines, the goal of a compressor rotor is to increase the angular momentum of the air by imparting an increase in swirl velocity. (Note: the goal of ...
interested22's user avatar
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1 answer
254 views

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 ...
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How does a fan in a turbofan engine suck air in?

I watched lots of video related to sucking process of a fan in a turbofan engine, but I'm confused at a point. In this link and many videos like this, I found the fan'...
Jawel7's user avatar
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7 votes
5 answers
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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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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? ...
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1 answer
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From which jet engine is this blade?

Some years ago I bought a compressor blade on ebay but I don't know which jet engine it's from. It's quite light. I tried to determine the density by the help of my kitchen equipment and it's most ...
Rednose's user avatar
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4 votes
2 answers
436 views

Airflow through axial flow compressor

So I'm reading the Gas Turbine Engine Fundamental, and suddenly come across the airflow passes through one axial compressor stage. I wonder why the Resultant Rotor Inlet Velocity is pointing downward,...
John Enrique's user avatar
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3 answers
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Is this image of Compressor aerodynamics correct?

Image Source: Air Gas Turbine Technology by Treager, Chapter 5 The rotation direction of rotor shown seems opposite. If it is correct, these are the questions I would like to ask: Why the Y vector is ...
Noorul Quamar's user avatar
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What is a ram recovery point?

As aircraft speed increases, thrust tends to decrease somewhat; as the aircraft speed reaches a certain point, ram recovery compensates for the losses caused by the increases in speed. The inlet must ...
Noorul Quamar's user avatar
2 votes
2 answers
4k 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?
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How does a C208B's climate control system that utilizes bleed air for cabin heat work?

I'm studying the systems on my first turbine-engine aircraft, specifically, a C208B. I know that there is "bleed air heat" that mixes with re-circulated cabin-air. I know that the bleed air ...
Ryan Mortensen's user avatar
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Why is it that low fuel gauge is one indication of a compressor stall?

I am reading from my gas turbine engine class notes that apparently, one indication of compressor stall (besides the banging sounds, torque gauge low, N1 low, ITT gauge up, etc) is the fuel levels ...
YamchaAviator's user avatar
4 votes
3 answers
2k views

How are compressor disks connected to the shaft?

I am trying to learn how compressor disks and shaft are connected each other. I don't have any idea about the terminology so I couldn't find anything useful. Here is a section view of a sample and I ...
Ali Yılmaz's user avatar
2 votes
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 to compare compressors of different efficiencies and pressure ratios?

I have two different engines, the CFM56, and the CFM LEAP-X. I roughly know the design point (take-off) isentropic efficiency and the pressure ratio for the LPC/HPC for both of them which are ...
Harjot Singh's user avatar
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2 answers
539 views

What is a typical compression ratio in light turboprop aircraft propellers? [closed]

Does anyone happen to know a rough estimate of a typical light turboprop aircraft propeller's compression ratio? Something with 6-12 seats like a Cessna Caravan or Piper Malibu. Doesn't need to be ...
Mikey Patterson's user avatar
2 votes
2 answers
174 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?
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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 ...
user39178's user avatar
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2 votes
3 answers
327 views

What causes air to move to combustor?

I know the pressure is highest at end of compressor. But what forces air to move low to higher pressure? Am i missing out something? I have heard seals are used to prevent leakage of air from ...
Auberron's user avatar
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How to determine the number of compression stages given a compression ratio?

I have a personal project to design a gas turbine engine, the main problem that puzzles me is how do I determine the pressure rise in each stage of an axial compressor? Say, I'm planning on a 38:1 ...
Salmonbeing00's user avatar
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1 answer
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Why are inlet vanes used instead of variable geometry inlets to prevent compressor surge/stall?

Jet engine core axial compressors (that of subsonic turbofans anyway) are designed to keep air flowing the right way at max RPM(or close to it). Below that, the airflow slows more and more, and ...
Abdullah is not an Amalekite's user avatar
5 votes
2 answers
2k views

Why is a centrifugal compressor in aircraft engine less susceptible to stall and surge?

I have came across a similar question here. Although the answer doesn't explain much about why and is somewhat vague. I have read that centrifugal compressor can achieve a higher pressure rise per ...
Abhishek P G's user avatar
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547 views

What is a compressor cascade?

Is a compressor cascade just the representation of the blade ring of an actual turbomachine? What is the difference between linear cascade and annular cascade? A diagram or a reference would be great.
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Which compressor is more like to surge and stall - axial or centrifugal?

I am studying about stall and surge in rotodynamic compressors and want to understand which one is more prone to these phenomena.
Aditya Shiva Appalla's user avatar
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1 answer
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Will an axial compressor work with an ideal fluid?

Will an axial compressor, like the one described starting on page 275 of Mechanics and Thermodyanmics (PDF link), work if the flow was assumed to be ideal (i.e. incompressible and inviscid)? ...
eball's user avatar
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8 votes
4 answers
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Do modern jet engines need igniters?

I've read that modern aircraft don't need spark plugs like conventional aircraft do, as the jet fuel autoignites once it's mixed with the hot air exiting from the compressors. Then why do aircraft ...
Johnson's user avatar
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2 answers
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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'...
Johnson's user avatar
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3 votes
1 answer
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Why are liquid ring compressors not used in a jet engine?

A question has been asked here before whether sliding vane compressors could be used in place of axial compressors on jet engines since they have a high compression ratio per stage (Why were rotary ...
Francis L.'s user avatar
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3 votes
2 answers
249 views

Are compressor maps for multistage compressors drawn for one blade row or the whole compressor?

Apologies if this is a stupid question. I am a little confused about compressor maps. Are compressor maps such as this one, drawn for one blade row only or the whole compressor? (source: Wikimedia) ...
Hypatie D'Alexandrie's user avatar
2 votes
0 answers
59 views

Is there a way to determine maximum rpm for axial compressor due to material limitations?

I'm looking for RPM to Stress relation to determine maximum rotational speed that compressor/turbine blades can have without undergoing deformation due to centrifugal tensile stress. I've come come ...
Ammar Ghori's user avatar
2 votes
1 answer
766 views

On a centrifugal compressor impeller what is the difference between the radial vanes and rotating guide vanes?

I thought the radial vanes were a machined part of the impeller that just force the airstream radially? And that another name was rotating guide vanes as they are rotating with the impeller disc.. But ...
Jono 's user avatar
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2 votes
3 answers
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On a axial flow turbo fan or turbo jet engine what comes first the rotor or the stator?

I've been let to understand that one stage consists of a row of rotors and stators. But I'm not sure which comes first? Does the front fan blades make the first part of the stage (rotor) with a stator ...
Jono 's user avatar
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21 votes
5 answers
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Why do airplanes use an axial flow jet engine instead of a more compact centrifugal jet engine?

Axial flow jet engines take up a lot of space. Centrifugal jet engines create high pressure. Can you create a centrifugal air pump that pushes as much air as a axial jet engine. Centrifugal air ...
Useruuu's user avatar
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4 votes
1 answer
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Are turbine and compressor blades and vanes cast or forged?

I was wondering how blades and vanes are typically made in commercial jet engines. Would you typically use investment casting to make compressor blades or just in the turbine section to accommodate ...
Greg M's user avatar
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1 vote
0 answers
21 views

In the compressor characteristic, how do I calculate the minimum flow?

I have a small question, how do I determine the minimum flow point on the compressor characteristic? I.e. what is the safety margin on the curve?
d saline's user avatar
1 vote
1 answer
199 views

In the compressor characteristic, what does this value represent?

$$ ? = \frac{m_t* \sqrt{T_3}}{P_3}$$ All I know is that it is a material property of a turbine, it has something to do with the mach number, and is used for calculating $W_T$. It's kinda similar to ...
d saline's user avatar
2 votes
2 answers
5k views

Is overall pressure ratio same as compressor pressure ratio for a gas turbine engine?

For a typical gas turbine engine, turbofan in particular, is the compressor pressure ratio same as the overall pressure ratio? For modelling purposes can we use the same value of overall pressure ...
smrithi s's user avatar
1 vote
1 answer
291 views

What values can/should be used for the isentropic efficiency of a compressor and turbine?

I was trying to model an turbofan aircraft engine using Matlab and Simulink. In the process I have fixed certain parameters to some specific values which are nominal operating values of the parameters....
smrithi s's user avatar
4 votes
1 answer
642 views

Are low pressure (LP) compressors and booster compressors the same thing?

Based on the above picture, are "LP compressor" and "Booster compressor" different names for the same thing or are they actually different things?
sherline lin's user avatar
5 votes
2 answers
1k views

Do any propellers/propfans use stator vanes? Why is this not a commonplace feature?

I understand that axial-flow turbine engines generally include stator vanes behind every(?) compressor and turbine stage. This makes quite intuitively sense, because without them the rotating blades ...
leftaroundabout's user avatar
3 votes
3 answers
491 views

Would there be a purpose for a set of compressors in an electric turbo fan?

This is actually a two part question. Would there be a purpose to a compressor in an electric turbofan where there is no need for a combustion chamber, and if not, is there then a purpose for a bypass ...
No One's user avatar
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-1 votes
1 answer
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How to understand turbo machines?(compressors,fans,pumps,turbines,etc..)

From what I understood, the energy transfer between the blades and the fluid(fluid to blade or blade to fluid) occurs due to the curvature of the blade.Its because of this curvature the stream of the ...
Mohan's user avatar
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6 votes
2 answers
719 views

How are compressor maps drawn?

I've always thought they are empirically derived: once you have your axial compressor phisically in a bench, you set both a rotational speed and a mass flow throught the turbomachine then you measure ...
XF-91's user avatar
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