05 Cycles Used in Jet Engines

7/30/2019 05 Cycles Used in Jet Engines

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Cycles usedin Jet Engines

CLASS 5


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Jet enginesJet engines move the airplane

forward with a great force that isproduced by a tremendousthrust and causes the plane tofly very fast.

All jet engines, which are alsocalled gas turbines, work on thesame principle.


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Jet engines

The image below shows how theair flows through the engine.

The air goes through the core ofthe engine as well as around thecore.

This causes some of the air to be

very hot and some to be cooler. The cooler air then mixes with the

hot air at the engine exit area.


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What is Thrust?

Thrustis the forward force thatpushes the engine and, theairplane forward.

An engine uses principle:

"every action there is anequal and opposite reaction."


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Jet TrustThe engine takes in a large

volume of air.The air is heated and

compressed and sloweddown.

The air is forced throughmany spinning blades.


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Jet Trust By mixing this air with jet

fuel, the temperature of theair can be as high as threethousanddegrees.

The power of the air is used toturn the turbine.


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Jet TrustFinally, when the air

leaves, it pushesbackward out of theengine.

This causes the plane tomove forward.


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Jet Engine Design1

2 3 4 56

diffuser

compressor

combustion chamber turbine nozzle

1

2

3

4

5

6

P=constant

P=constant

qout

qin

T

s

1-2 Isentropic compression in diffuser

2-3 Isentropic compression through compressor

3-4 Constant pressure heat additionin combustion chamber

4-5 Isentropic expansion through turbine

5-6 Isentropic expansion in nozzle

6-1 Constant pressure heat rejection

Idealized air-standard

Brayton cycle


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Isentropic

compressionCompression which

occurs without anychange in entropy.

Entropy =

"disorder"(Greek)


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Parts of a Jet Engine


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FanFan - The fan is the first component in aturbofan. The large spinning fan sucks in

large quantities of air. Most blades of thefan are made of titanium. It then speedsthis air up and splits it into two parts. Onepart continues through the "core" or

center of the engine, where it is actedupon by the other engine components.


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FanThe second part "bypasses" the core ofthe engine. It goes through a duct that

surrounds the core to the back of theengine where it produces much of theforce that propels the airplane forward.This cooler air helps to quiet the engine as

well as adding thrust to the engine.


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CompressorCompressor - The compressor

is the first component in theengine core.The compressor is made up

of fans with many blades and

attached to a shaft.


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Compressor The compressor squeezes the air

that enters it into progressively

smaller areas, resulting in anincrease in the air pressure.

This results in an increase in theenergy potential of the air.

The squashed air is forced intothe combustion chamber.


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Combustor

Combustor - In the combustorthe air is mixed with fuel and

then ignited.There are as many as 20 nozzles

to spray fuel into the airstream.

The mixture of air and fuelcatches fire


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Combustor

This provides a high

temperature, high-energyairflow.

The fuel burns with theoxygen in the compressed

air, producing hotexpanding gases.


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Combustor

The inside of the

combustor is often made ofceramic materials toprovide a heat-resistant

chamber.The heat can reach 2700.


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Turbine

Turbine - The high-energy airflowcoming out of the combustor

goes into the turbine, causingthe turbine blades to rotate.

The turbines are linked by ashaft to turn the blades in the

compressor and to spin theintake fan at the front.


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Turbine

This rotation takes some energyfrom the high-energy flow that is

used to drive the fan and thecompressor.

The gases produced in thecombustion chamber move

through the turbine and spin itsblades.


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Turbine

The turbines of the jet spin

around thousands of times.They are fixed on shafts

which have several sets of

ball-bearing in betweenthem.


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Nozzle

Nozzle - The nozzle is the

exhaust duct of theengine.This is the engine part

which actually producesthe thrust for the plane.


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Nozzle

The energy depleted airflow thatpassed the turbine, in addition to

the colder air that bypassed theengine core, produces a forcewhen exiting the nozzle that actsto propel the engine, and

therefore the airplane,forward.


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Nozzle

The combination of the

hot air and cold air areexpelled and producean exhaust, whichcauses a forward thrust.


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mixerThe nozzle may be preceded by

a mixer, which combines the

high temperature air comingfrom the engine core with thelower temperature air that wasbypassed in the fan.

The mixer helps to make theengine quieter.

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05 Cycles Used in Jet Engines