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Unit 5 > Turbine > Flashcards

Turbine Flashcards

1
Q

Turbine engines work like

A

Propane barbeque

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2
Q

Major difference between gas turbine and turbocharged

A

A turbo charged engine is a piston powered engine that has the air compressed for it so that it increases the density of the air flowing into the cylinders. These engines involve reciprocating motion and intermittent combustion.

A gas turbine engine is not piston powered. Instead these Indians have rotating parts with continuous airflow and continuous power production

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3
Q

What is the one similarity of gas turbine engine with piston engines

A

They also have four strokes but they work a bit different

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4
Q

Name four type of gas turbine or ‘jet engines’

A

Turbojet engine
Turbofan engine
turboprop engine
turbo shaft engine helicopters

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5
Q

Most basic type of gas turbine engine is

A

Turbojet engine

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6
Q

What is the principle of turbojet engine how do the work

A

Basically air is brought in through the front of the engine compressed heated expanded and accelerated out the back. Since the heated air exit velocity is greater than the free Stream or entrance velocity thrust is created.
We won’t use the term thrust for turbo prop we will use power or torque

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7
Q

Unlike the piston engine, gas turbine engine has a maximum or a minimum moving part?

A

They have minimum moving parts and have a smooth flow

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8
Q

Interbo jet engine large amount of surrounding air are Continuously brought into the engine through

A

Inlet or intake

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9
Q

In turbojet engine what comes after the inlet

A

At the rear of the inlet the air Enters the compressor

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10
Q

Name two main types of compressor

A

Axial flow -efficient but lots of stages required
Centrifugal flow -less efficient but smaller and lighter

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11
Q

Compressor with big fins

A

Low pressure compressor

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12
Q

What kind of pressure is created by a smaller fins Compressor

A

High-pressure compressor

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13
Q

What is the difference between a rotor and a stator

A

The router is the part that rotates like those fins and the Strator is the part between the fins (also called the rotators) that doesn’t rotate.
Stator Converts kinetic energy into pressure

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14
Q

What is the rotator strator pair called

A

Stage

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15
Q

A Set a rotors to spinning together is called

A

Spool

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16
Q

What is the purpose of stator vanes or stators

A

Stator vanes are stationary and serve to convert the rotational energy into static pressure through the change in flow
This stop the swirling of air and increase the compression on it

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17
Q

Is centrifugal compressor spins the air in what direction

A

Outwards

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18
Q

Where are the centrifugal flow compressor usually found

A

It will typically be found at the end of a set or stages of axial compressors

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19
Q

What will a centrifugal compressor have instead of stators that will convert kinetic energy into pressure

A

Diffusers

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20
Q

After the compression in the diffuser where will the air go

A

Burnerrrrrrrrrrr

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21
Q

What does the diffuser do

A

The air comes through the inlet then to the compressor and because the air is very fast it will not burn properly so the diffuser slows it down when the air hits it creates a higher static pressure which improves the combustion efficiency

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22
Q

Do turbine engines run lean or Rich

A

Lean very lean

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23
Q

What is usually the ratio of a typical jet engine of fuel to air

A

In a typical jet engine two pounds of fuel is combined with 100 pounds of air. 70 to 80% of the air flow is not used in combustion

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24
Q

After the inlet compression diffuser and the burner where is the air sent

A

The hotter expended air is what gets sent into the turbine

25
Q

What would be the situation in which you have to keep igniter’s on

A

Like continuous rain

26
Q

Name three main types of burners

A

Annular -ring
can -cans
can-annular - ring with cans inside it

27
Q

How is a turbine different from the compressor it drives

A

Turbines won’t stall but the compressors will if you fly the airplane at a higher angle of attack because the compressor has those Vanes which are like tiny airfoils.
And turbines run with that hot gas

28
Q

How does an afterburner works

A

You introduce fuel into the following stages near exhaust which causes huge power and thrust. It is very complex and adds a lot of weight so it is normally found in military aircraft like Concord also it has poor fuel efficiency

29
Q

Is it turbine and compressor are linked by a

A

Central shaft

30
Q

Turbine and compressor shafts can be nested and we will have done multiple shaft speeds denoted as

A

N speeds like n1 spool less pressure and n2 spool more pressure

31
Q

Does turbine take some of the energy out of the exhaust and does it effect performance

A

Yes it does take some energy out of it but it still has a lot of energy that is left to provide thrust so no It doesn’t affect any performance

32
Q

Exhaust guesses are then vented through wht part

A

Nozzle, they can slightly aid in the aircrafts thrust n make it quiter

33
Q

What is the modern variation of the gas turbine engine

A

Turbofan turbine engine

34
Q

How does the Turbofan engine works

A

It basically works like the same principal of gas turbine engine but now the turbine shaft powers a fan in front of the inlet which creates thrust around the engine and some air is sent inside the core engine with the 4stroke process also that creates thrust n rotates the fan

35
Q

Which is more fuel efficient turbo fan or turbo jets

A

Purple fan is 30 to 40% more fuel efficient than turbo jets there also more quieter

36
Q

What is a bypass ratio

A

The ratio of the air that goes around the engine to the air that goes through the core is called the bypass ratio

37
Q

What does low by pass ratio means

A

Bypass ratio gives us information about the performance of Turbofan engine
BPS Ratio less than 5:1
Higher fuel consumption higher speeds

38
Q

What is high bypass ratio

A

BPR of 5:1 or more
Lower fuel consumption and much quieter. The fan generates 80% of the thrust

39
Q

What is Engine pressure ratio

A

It is the ratio of the turbine outlet pressure to the compressor inlet pressure
Usually used to know thrust

40
Q

How do turboprop work

A

Everything is same like turbine engine in this in this case instead of expelling all the hot exhaust gas most of the energy is used to turn the power turbine which drives a propeller through a gearbox which provides all the trust

41
Q

In a single shaft engine which two turbines become one

A

The compressor turbine and the power turbine

42
Q

What is the exhaust velocity of a turbo prop

A

The exhaust velocity of a turbo prop is low because most of the exhaust energy is extracted by the power turbine so the produce only a little bit of jet trust but a lot of TORQUE in this case

43
Q

Name two ways to provide power to turboprop

A

Direct drive- the compressor turbine and power turbine are the same turbine
free turbine- The compressor shaft and the power shaft rotate independently, sometimes in the wind u will see them spinning without power

44
Q

How does a turboshaft works

A

used for helicopters turboshaft is similar to turboprop engine because it has free turbine type the different thing is it’s function used for helicopters

45
Q

Name some other uses for turboshaft engine

A

Other uses for turboshaft engine could be driving compressors, electrical generators, pumps and marine applications

46
Q

Which turbo type performs good in lower speeds

A

Turbo prop are actually better at lower speeds

47
Q

Which turbo type performs good at high altitude and high speed

A

Turbo jets are very efficient at high speeds however they perform poorly and waste energy at low speeds

48
Q

Which turbo type is actually better in all of these

A

Turbofans are the best compromise between turboprops and turbojets

49
Q

How can you use compressor bleed air

A

You can bleed air from the compressor and used for other systems for example air from Low speed compressor will have less psi and a lower temperature it can be used for Cabin pressurization
Air from a high speed compressor will have high PSI and high temperature this can be used for deicing

50
Q

What are auxiliary power units APU

A

How many turbine powered airplanes will have a hidden mini turbine engine in the tail to start electrical system of plane and provide pressure to spin the compressor for starting

51
Q

Is starting the turbine engine different from piston engine

A

Yes if you have a tail vent it could badly damaged the turbine engine so make sure you’re facing the wind typically you will need up to 12% of the normal compressor speed for starting n ignite the fuel
To obtainthis speed there are two ways.
Via starter or generator
Thru pneumatic which is thru forced air pressure thru apu or gpu to ‘light up’ or igniter speed

52
Q

What will happen if the fuel is injected into the burner to early

A

There will not be enough pressure in the engine to throw out all the hot air towards the back through the power turbine this will cause the fuel to burn in the burner area and the engine will melt

53
Q

After firing the igniter’s what should you carefully monitor

A

Carefully monitor the N1 speed and the EGT temperature
500°F degrees EGT happens after 20% n1 then all is OK if before then not

54
Q

What is hung start

A

Condition of Normal light off but with rpm at the lower value rather than normal idle rpm.
It is very similar to hot start but in this case not enough cooling air is going through the compressor and it is not due to improper compressor speed but because of not enough power for high density altitude for fuel control malfunction

55
Q

How are compressor stalls caused

A

By excessive angle of attack The air falls in the compressor are loaded above their lifting capacity

56
Q

What are the symptoms of compressor stalls and how to recover

A

You will hear a loud bang strong vibration loud roar
to recover immediately reduce power, decrease the angle of attack, increase in speed

57
Q

In typical jet engine what pounds of air per second is combined with only what pounds of fuel per second

A

100,5

58
Q

What is re heat

A

Same as after burner

59
Q

An after burner increases what and reduces what

A

Power, efficiency

Unit 5 (3 decks)

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