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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1answer
71 views

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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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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143 views

Turbines in jet engines

I was reading this thread and in the answer, the person wrote "For example, the turbine blades are replaced after a set number of turbine cycles and/or after a set number of hours, which are lesser ...
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138 views

How often are turbine blades in jet engines replaced?

How often are the turbines in the hot section of the jet engines replaced due to deteriorated TBC? or just how often are they replaced? lets say for CFM56-7
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What is the definition of “blade scatter” in gas turbine compressor dynamic balancing?

Can someone help me define “blade scatter” gas turbine compressor dynamic balancing?
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443 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
269 views

What is the correct equation for rotor solidity?

I'm working in a project that uses"blade solidity ratio", or "rotor solidity", the problem is, there are several articles which defines the equation in a different way changing in the section of the ...
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365 views

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 ...
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Would turbine blade twist change if all conditions except the density of the fluid remained the same?

While designing a turbine, the blade twist is apparent from the velocity triangles, and this analysis only depends on the velocity. However, would there be any difference for different media? When ...
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What is the relation between solidity and lift coefficients?

I've seen this graph in a couple of places. I'm not sure what it's supposed to mean, as the formulae I've seen in the papers cannot be found in any standard book or reference. Please let me know if ...
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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?
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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 ...
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112 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....
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How is static droop achieved in mechanical governors

The Bendix power turbine governor in the Bell 206 is just simple flyweight arrangement which controls a pneumatic signal to the FCU. How is static droop achieved in this type of system?
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581 views

I wonder if it's possible to make a “compressed air” turbine engine [closed]

I wonder if it's possible to make an efficient turbine engine that uses only hot compressed air to move but only that, meaning there is no ignition involved. To put it simple can we use compressors ...
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What is the difference between active tip clearance control system and passive tip clearance control system in turbine?

What are the main differences between turbine active tip clearance control system and passive tip clearance control system?
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964 views

Is low pressure compressor air used to cool turbine blades?

This photo shows LP cooling air is being used to cool turbine blades. the question is, is it possible to use LP air to cool the turbine blades? would you please guys explain why do they use LP air ...
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925 views

What is the efficiency of the turbine of a modern jet engine?

What is the turbine efficiency of a modern jet engine? Just the turbine efficiency only. What percentage of fuel energy the turbine converts into mechanical energy.
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Does the stator blade angle changes? Why?

I have read that when jets are on the ground their compression ratio changes. With this change the stator compressor's blade angle changes. Is this true?
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What does the term “loading” refers to when we talk about Blade loading and Stage loading in Turbomachinery?

I have been reading about the term Blade Loading and Stage loading in case of Axial Turbines and Compressors, however, I would like to know what does the term "loading" here exactly refers to? What I ...
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Hydro-pneumatic fuel controls and hydro-mechanical fuel controls

What are the advantages and disadvantages of the hydro-pneumatic controls against the hydro-mechanical controls?
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648 views

Gas Turbine Engine Starting Sequence [closed]

How to explain the figure above?
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1answer
715 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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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 ...
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How are turbine blades overhauled?

How are turbine blades overhauled? What techniques are commonly used and how does it affect the integrity of the blade?
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Why is the first turbine in a turboprop (or turboshaft) connected to the compressor?

Typically the first turbine after the combustion chamber drives the compressor as shown in this picture. (wikimedia.org) This first turbine spins the fastest and harvests the most energy from the ...
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How many turbine powered aircraft are in the air at any given time? [closed]

I know there are a lot of statistics about how many planes are in the air on average, but not all aircraft flying are turbine-driven. How may turbojet, turbofan, and turboprop aircraft, on average, ...
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684 views

What were the J47's turbine blades made of?

What materials were used to make the General Electric J47 turbine blades in the 1960's?
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614 views

Would removing heat from the compressor and adding heat to the turbine increase a gas turbine's efficiency?

Since a compressor compresses air, the air temperature increases due to P1/T1=P2/T2. When the temperature is increased it would be harder to compress - so would removing the heat from the air inside ...
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399 views

What is the market size of high-pressure turbine blades for commercial aircraft? [closed]

I need to calculate the market size for high pressure turbine blades which are used in commercial aircraft. I am working on a business school project on this topic. Any information which can be used ...
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Why are Jet Engine fan blades (and other turbomachinery blades) cantilevered rather than being connected together at their outer edges? [duplicate]

It seems to me that connecting the outside edges of each blade together would create a stiffer structure with lower stresses and a better fatigue life for a given operating condition.
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What is the purpose of a fuse pin in a turbine engine?

what's the difference betweeen fuse pin and mounting bolts of an engine ? Are they the same ? Any digram of a GE-90 engine showing those would be appreciated.
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543 views

Why is a contra-rotating High Pressure section more efficient? [duplicate]

In the Rolls Royce Trent 900 marketing material, the use of contra-rotating HP system is described as increasing the efficiency of the engine. Can anyone explain why/how that increases the efficiency?
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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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What are the effects of angle of attack on turbines in composed delta wings with jets in upper side?

: a layperson doubt. What would happen during take-off and landing of a machine as Boeing X-48, because of the high angle of attack, the steep attitude of the airplane: would this difficult air supply ...
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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 ...
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Why are there curved blades on jet engines? [duplicate]

On the fan and comssorssor and turbine for that matter there are blades and they are also curved. Im already confused beucase the fan has blades but wouldn't it blow out air not suck in air? Why are ...
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314 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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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 ...
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What is the difference between single and dual annular combustor?

CFM56 uses single annular and GEnX uses dual annular combustion chamber. somebody please explain with pics.
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Where can I find information about the number of blades and vanes in jet engines?

Is there any website or database that I can find the numbers of turbine blades and vanes per each stage of turbine in a jet engine?
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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 ...
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748 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?
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What is the link OR difference between change in momentum & pressure difference?

I ask in regards to the the thrust formula, which includes change in momentum, as well as difference in pressure between inlet & outlet of the engine to calculate generated thrust; this implies ...
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Is there an engine database that would include information on number of HPT blades per engine?

I am attempting to compile information on the number of high-pressure turbine blades across a wide range of turbine engines. Currently, I have only been able to find this information through brut ...
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437 views

How are the compressor and turbine disks connected?

What is the typical way the compressor and turbine disks connected to (LP/HP) shaft ? How are the disks connected to each other (e.g., curvic coupling, bolts or others ?)
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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 ...
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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 ...
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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 ...