It is all about Gas Turbine and its features. Enjoy.

1. GasGas
TurbinesTurbines

2. IntroductionIntroduction
 Gas-turbine engine:Gas-turbine engine: Any internal combustion Any internal combustion
engine, employing aengine, employing a gasgas as the working fluid whichas the working fluid which
is used to turn a is used to turn a turbineturbine..
 The term also is conventionally used to describe aThe term also is conventionally used to describe a
complete internal combustion engine consisting ofcomplete internal combustion engine consisting of
at leastat least
• A compressor,A compressor,
• A combustion chamber, andA combustion chamber, and
• A turbine. A turbine.
In the gas turbine, there is a continuous flow of
the working fluid.

3. ApplicationsApplications
 The outgoing gaseous fluid (exhaust) can be used
to generate thrust. Useful work or propulsive thrustUseful work or propulsive thrust
can be obtained from a gas-turbine engine.can be obtained from a gas-turbine engine.
 It may drive aIt may drive a generator, pump, or propellergenerator, pump, or propeller or, inor, in
the case of a purethe case of a pure jet aircraft enginejet aircraft engine, develop thrust, develop thrust
by accelerating the by accelerating the turbine exhaust flow through a exhaust flow through a
nozzle (e.g. after-burner).nozzle (e.g. after-burner).

4. 44

5. 55

6. BraytonBrayton
CycleCycle

7. Working PrincipleWorking Principle
 This working fluid is initially compressed in the
compressor.
 It is then heated in the combustion chamber.
 Finally, it goes through the turbine.
 The turbine converts the energy of the gas into
mechanical work.
 Part of this work is used to drive the compressor.
The remaining part is known as the net work of the
gas turbine.

8. Cont…
 When examining the gas turbine cycle, we
make a few assumptions.
The working fluid is a perfect gas .
The kinetic/potential energy of the
working fluid does not vary along the gas
turbine.
Finally, pressure losses, mechanical
losses and other kinds of losses are
ignored.

9. Variant:Variant:
Closed Brayton CycleClosed Brayton Cycle
 A closed Brayton cycle re-circulates the A closed Brayton cycle re-circulates the
working fluidworking fluid, the air expelled from the, the air expelled from the
turbine isturbine is reintroducedreintroduced into the compressor.into the compressor.
 This cycle uses a This cycle uses a heat exchangerheat exchanger to heat to heat
the working fluid instead of an internalthe working fluid instead of an internal
combustion chambercombustion chamber..
 The closed Brayton cycle is used forThe closed Brayton cycle is used for
example in example in closed-cycle gas turbineclosed-cycle gas turbine and and
space power generation.space power generation.

11. ClassificationClassification

12. The Ideal Gas Turbine Cycle
(Closed Brayton Cycle)
Turbine
gives drive
to run the
compressor

13.  Work done by Turbine per kg of air,Work done by Turbine per kg of air,
WWTT = c= cpp (T(T33-T-T44))
Note: For Isentropic expansion,Note: For Isentropic expansion,
Work Done = Mass (m) X Specific heat at constantWork Done = Mass (m) X Specific heat at constant
Pressure (cPressure (cpp) X Change in Temperature) X Change in Temperature
or,or, W= m. cW= m. cpp(T(T33-T-T44))

14.  Work required by Compressor per kg of air,Work required by Compressor per kg of air,
WW cc = c= cpp (T(T22-T-T11))
Note: For Isentropic compression,Note: For Isentropic compression,
Work Done = Mass (m) X Specific heat at constantWork Done = Mass (m) X Specific heat at constant
Pressure (cPressure (cpp) X Change in Temperature) X Change in Temperature
or,or, W= m. cW= m. cpp(T(T22-T-T11))

15.  Net Work available in a Gas Turbine,Net Work available in a Gas Turbine,
W= WW= WT-T- WWcc
or,or, WW = c= cpp (T(T33-T-T44) - c) - cpp (T(T22-T-T11))
or,or, WW = c= cpp {(T{(T33-T-T44) - (T) - (T22-T-T11)})}
 For Isentropic process,For Isentropic process,
TTSS/T/TLL = (p= (p SS / p/ p LL)^ ()^ (γγ-1-1)/)/γγ

16. Basic ComponentsBasic Components

17. Basic ComponentsBasic Components

18. Basic ComponentsBasic Components
 CompressorCompressor
– Draws in air & compresses itDraws in air & compresses it
 Combustion ChamberCombustion Chamber
– Fuel pumped in and ignited to burn withFuel pumped in and ignited to burn with
compressed aircompressed air
 TurbineTurbine
– Hot gases converted to workHot gases converted to work
– Can drive compressor & external loadCan drive compressor & external load

19. Basic ComponentsBasic Components
 CompressorCompressor
– Draws in air & compresses itDraws in air & compresses it
 Combustion ChamberCombustion Chamber
– Fuel pumped in and ignited to burn withFuel pumped in and ignited to burn with
compressed aircompressed air
 TurbineTurbine
– Hot gases converted to workHot gases converted to work
– Can drive compressor & external loadCan drive compressor & external load

20. Basic ComponentsBasic Components
 CompressorCompressor
– Draws in air & compresses itDraws in air & compresses it
 Combustion ChamberCombustion Chamber
– Fuel pumped in and ignited to burn withFuel pumped in and ignited to burn with
compressed aircompressed air
 TurbineTurbine
– Hot gases converted to workHot gases converted to work
– Can drive compressor & external loadCan drive compressor & external load

21. CompressorCompressor
 Supplies high pressure air forSupplies high pressure air for
combustion processcombustion process
 Compressor typesCompressor types
– Radial/centrifugal flow compressorRadial/centrifugal flow compressor
– Axial flow compressorAxial flow compressor

22. CompressorCompressor
 Radial/centrifugal flowRadial/centrifugal flow
– Advantages: simpleAdvantages: simple
design, good for lowdesign, good for low
compression ratioscompression ratios
(5:1)(5:1)
– Disadvantages: DifficultDisadvantages: Difficult
to stage,less efficientto stage,less efficient
 Axial flowAxial flow
– Good for highGood for high
compression ratioscompression ratios
(20:1)(20:1)
– Most commonly usedMost commonly used

23. Use of Compressed AirUse of Compressed Air
 Primary Air (30%)Primary Air (30%)
– Passes directly to combustor forPasses directly to combustor for
combustion processcombustion process
 Secondary Air (65%)Secondary Air (65%)
– Passes through holes in perforated innerPasses through holes in perforated inner
shell & mixes with combustion gasesshell & mixes with combustion gases
 Film Cooling Air (5%)Film Cooling Air (5%)
– Insulates/cools turbine bladesInsulates/cools turbine blades

24. Blade CoolingBlade Cooling

25. Combustion ChambersCombustion Chambers
 Where air & fuel are mixed, ignited,Where air & fuel are mixed, ignited,
and burnedand burned
 Spark plugs used to ignite fuelSpark plugs used to ignite fuel
 TypesTypes
– Can: for small, centrifugal compressorsCan: for small, centrifugal compressors
– Annular: for larger, axial compressorsAnnular: for larger, axial compressors
(LM 2500)(LM 2500)
– Can-annular: rarely usedCan-annular: rarely used

26. TurbinesTurbines
 Consists of one or more stagesConsists of one or more stages
 Designed to develop rotational energyDesigned to develop rotational energy
 Uses sets of nozzles & bladesUses sets of nozzles & blades
 Single shaftSingle shaft
– Power coupling on same shaft as turbinePower coupling on same shaft as turbine
– Same shaft drives rotor of compressorSame shaft drives rotor of compressor
and power componentsand power components

27. TurbinesTurbines
 Split ShaftSplit Shaft
– Gas generator turbine drives compressorGas generator turbine drives compressor
– Power turbine separate from gas generator turbinePower turbine separate from gas generator turbine
– Power turbine driven by exhaust from gas generatorPower turbine driven by exhaust from gas generator
turbineturbine
– Power turbine drives power couplingPower turbine drives power coupling

28. Dual Shaft, Split ShaftDual Shaft, Split Shaft

29. Improving Turbine EfficiencyImproving Turbine Efficiency
 IntercoolerIntercooler
– Compressing the air in two stages andCompressing the air in two stages and
using an intercooler between the two.using an intercooler between the two.

30. Improving Turbine EfficiencyImproving Turbine Efficiency
 ReheatingReheating
– Expanding the air in two stages and usingExpanding the air in two stages and using
a re-heater between the two.a re-heater between the two.

31. Other TypesOther Types
 Semi-Closed Cycle Gas TurbinesSemi-Closed Cycle Gas Turbines
– Combination of an open and a closedCombination of an open and a closed
cycle gas turbinescycle gas turbines
 Constant Pressure Gas TurbinesConstant Pressure Gas Turbines
– Air heated in combustion chamber atAir heated in combustion chamber at
constant pressureconstant pressure
 Constant Volume Gas TurbinesConstant Volume Gas Turbines
– Air heated in combustion chamber atAir heated in combustion chamber at
constant volumeconstant volume

32. Gas Turbine SystemsGas Turbine Systems
 Air SystemAir System
– Air intakes are located high up & multipleAir intakes are located high up & multiple
filtersfilters
– Exhaust discharged out stacksExhaust discharged out stacks
 Fuel SystemFuel System
– Uses either DFM or JP-5Uses either DFM or JP-5
 Lubrication SystemLubrication System
– Supply bearings and gears with oilSupply bearings and gears with oil

33. Advantages of gasAdvantages of gas
turbine enginesturbine engines
 Very high power-to-weight ratioVery high power-to-weight ratio
 More size efficientMore size efficient
 Moves in one direction only, with fewerMoves in one direction only, with fewer
moving partsmoving parts
 Low operating pressuresLow operating pressures
 High operation speedsHigh operation speeds
 Low lubricating oil cost andLow lubricating oil cost and
consumptionconsumption

34. Disadvantages of gasDisadvantages of gas
turbine enginesturbine engines
 More expensive compared to aMore expensive compared to a
similar-sized reciprocating enginesimilar-sized reciprocating engine
 More complex machining operationsMore complex machining operations
 Usually less efficient thanUsually less efficient than
reciprocating engines, especially atreciprocating engines, especially at
idleidle
 Delayed response to changes inDelayed response to changes in
power settingspower settings

35. ComparisonComparison
 Gas Turbines vs Steam TurbinesGas Turbines vs Steam Turbines
 Gas Turbines vs IC EnginesGas Turbines vs IC Engines
 Closed Cycle Gas Turbines vs OpenClosed Cycle Gas Turbines vs Open
Cycle Gas TurbinesCycle Gas Turbines

36. Questions?Questions?