UNIT-V FMM

AravindRa2 2,548 views 100 slides Sep 12, 2022
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About This Presentation

TURBINES


Slide Content

FLUID MECHANICS
AND MACHINERY
TURBINES

HYDRAULIC TURBINE
❖Itisamachinewhichconvertsthepressureand
kineticenergyofwatercalledhydraulicenergyinto
mechanicalenergy.
❖Thesearealsocalledaswaterturbines.
❖Themechanicalenergyofturbineisfurther
convertedintoelectricenergybyanelectric
generatorwhichisdirectlycoupledtotheshaftof
hydraulicturbine.

HYDRAULIC TURBINE
❖Theelectricalpowergeneratedisknownas
hydroelectricpower.
❖Hydraulicturbinesareefficient.
❖Thesehavelowwearandtearandeaseof
maintenance.
❖Thecapitalcostishighwithlonggestationperiod
duetotherequirementofconstructingthedam
acrosstheriverandlayingthelongpipelines.

CLASSIFICATION OF TURBINE
Turbine
Impulse Turbine Reaction Turbine
Pelton
Wheel
Girard
Turbine
Francis
Turbine
Kaplan
Turbine
Propeller
Turbine
Turgo
Turbine

GENERAL LAYOUT OF A HYDRO ELECTRIC POWER PLANT

GENERAL LAYOUT OF A HYDRO ELECTRIC POWER PLANT

GENERAL LAYOUT OF A HYDRO ELECTRIC POWER PLANT
❖Adamwhichisconstructedacrossarivertostorewater.
❖Itprovidesnecessarypotentialenergytonozzlesofa
turbine.
❖Itactsaswaterreservoir.Topsurfaceofwaterindamis
calledheadrace.
❖Thepenstockisalargediameterpipeusuallymadeof
reinforcedconcreteorsteel.
❖Itcarrieswaterunderpressurefromthewaterstoredina
damorreservoirtotheturbines.

GENERAL LAYOUT OF A HYDRO ELECTRIC POWER PLANT
❖AWaterturbinewhichconvertshydraulicenergyinto
mechanicalenergy.
❖Awaterturbinecanbesethorizontalorvertical.The
choiceisgovernedbycost,typeofturbine,buildingspace
andplantlayoutetc.
❖Atailraceisadischargecanalintowhichwateris
dischargedfromtheturbine.
❖Differenceofheadraceandtailraceleveliscalledgross
head,H
g.

PELTON WHEEL OR PELTON TURBINE
❖Peltonwheelisatangentialflowimpulseturbine.
❖InPeltonturbinesthewaterstrikesthebuckets
alongthetangentoftherunnerorwheel.
❖Itisusedforhighheadsmorethan100mofwater.
Theseturbineshavebeenbuiltuptoaheadof
1600m.

CONSTRUCTION AND WORKING OF PELTON WHEEL

CONSTRUCTION AND WORKING OF PELTON WHEEL
❖ThemaincomponentsofaPeltonwheelare
❖Nozzleandspearassembly
❖Runnerandbuckets
❖Casing
❖Brakingjet
❖Deflector

CONSTRUCTION AND WORKING OF PELTON WHEEL
❖NOZZLE AND SPEAR ASSEMBLY
❖Theneedlespearisprovidedinthe
nozzletoregulatethewaterflow
throughthenozzle.
❖Itprovidesthesmoothflowofwaterwithnegligibleloss
ofenergy.
❖Aspearisaconicalneedlewhichcanbemovedinaxial
directionbyoperatingthewheeleithermanuallyor
automatically.

CONSTRUCTION AND WORKING OF PELTON WHEEL
❖NOZZLE AND SPEAR ASSEMBLY
❖Whenthespearismovedinforward
directionintothenozzle,itreducedthe
nozzleexitarea,hence,thequantityof
waterflowstrikingthebucketsis
reduced.
❖Ifthespearismovedbackwards,itincreasestheflowrateofwater.
❖Thenozzleconvertsthepotentialenergyofwaterintokinetic
energybeforejetstrikesthebuckets.

CONSTRUCTION AND WORKING OF PELTON WHEEL
❖RUNNER AND BUCKETS
❖Theturbinerotorcalledrunnerisa
circulardiscfixedwithbuckets.
❖Itisprovidedwithcylindricalbossand
keyedtothesupportingshaftinsmall
thrustbearings.
❖Therunnercarriescup-shapedbucketsmorethat15innumber
whicharemountedatequidistancearounditsperiphery.
❖Thebucketsareeithercastintegrallywiththecirculardiscor
theseareboltedindividuallytotherunner,ithelpsineasy
replacementofbucketswhenwornout.

CONSTRUCTION AND WORKING OF PELTON WHEEL
❖RUNNER AND BUCKETS
❖Theturbinerotorcalled
runnerisacirculardiscfixed
withbuckets.
❖Itisprovidedwithcylindricalboss
andkeyedtothesupportingshaftin
smallthrustbearings.
❖Therunnercarriescup-shapedbucketsmorethat15innumber
whicharemountedatequidistancearounditsperiphery.

CONSTRUCTION AND WORKING OF PELTON WHEEL
❖RUNNER AND BUCKETS
❖Thebucketsareeithercast
integrallywiththecircular
discorthesearebolted
individuallytotherunner,it
helpsineasyreplacementof
bucketswhenwornout.
❖Bucketsaremadeofcastironcaststeel,specialsteelsorstainless
steelwithinnersurfacepolishedtoreducefrictionlossesofwater
jet.

CONSTRUCTION AND WORKING OF PELTON WHEEL
❖RUNNER AND BUCKETS
❖Theshapeofthebucketsisof
doublehemisphericalcupor
bowl.
❖Eachbowlofthebucketis
separatedbyawallcalled
splitteroraridge.
❖Thewaterstrikesthebucketatthesplitterwhichsplitsthewater
intotwoequalstreamsofthehemisphericalbowl.

CONSTRUCTION AND WORKING OF PELTON WHEEL
❖RUNNER AND BUCKETS
❖Themaximumforcewillbe
obtainedwhenthejetis
deflectedthrough180°into
exacthemisphericalbowl.
❖Inpracticethejetisdeflectedthrough160°to170°
❖Itavoidsstrikingtheexitjetwiththebackofthesucceeding
bucket,thusexertingaretardingforceonit.
❖Thisalsoavoidsthesplashingofwaterwithasplitter.

CONSTRUCTION AND WORKING OF PELTON WHEEL
❖RUNNER AND BUCKETS
❖Peltonwheelisprovidedwith
twohemisphericalcupssince
thesplittersplitsthejetinto
twoequalstreams,theaxial
componentofeachstream
velocityisequalandopposite
duetowhichtheaxialthrust
bntheshaftisnegligible
❖Peltonwheelneedsverysmallthrustbearings.

CONSTRUCTION AND WORKING OF PELTON WHEEL
❖RUNNER AND BUCKETS
❖Anundercutisprovidedand
surfaceofspoonsisraisedso
thatwatercanbedeflected
backthroughtheangleof160°
to170°withthevertical
without disturbingthe
incomingbucket.

CONSTRUCTION AND WORKING OF PELTON WHEEL
❖BRAKING JET
❖Theturbineisbroughttorest,thenozzle
iscompletelyclosedbypushingforward
thespear.
❖Therunnercontinuestorotateduetoits
inertiaforaconsiderableperiodoftime
tillitcomestorest.
❖Inordertobringtherunnertostopinashortesttime,asmall
nozzleisprovidedwhichissuesthewaterjetandfallsontheback
ofbuckets.
❖Itactsasahydraulicbrakeforreducingthespeedofrunner.

CONSTRUCTION AND WORKING OF PELTON WHEEL
❖DEFLECTOR
❖Adeflectorisprovided
whichishingedtothe
casingtodeflectthejetof
waterawayfromstriking
thebucketsincasethe
loadonturbinesuddenly
reduces.
❖Itpreventstherunnerofturbineattainingunsafespeedscalled
runawayspeed.

VELOCITY TRIANGLE OF PELTON WHEEL
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VELOCITY TRIANGLE OF PELTON WHEEL

FORMULA USED
❖WORK DONE BY JET PER SECOND
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❖HYDRAULIC EFFICIENCY
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FORMULA USED
❖OVERALL EFFICIENCY
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FORMULA USED
❖DISCHARGE OF SINGLE JET
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FORMULA USED
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FORMULA USED
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FORMULA USED
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❖POWER LOST IN RUNNER
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FORMULA USED
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FORMULA USED
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❖SPECIFIC SPEED
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PROBLEM 1
APeltonwheelhasameanbucketspeedof10m/swithajetof
waterflowingattherateof0.7m
3
/sunderaheadof30m.The
bucketsdeflectthejetthroughanangleof160°.Calculatethe
powergivenbythewatertotherunnerandthehydraulic
efficiencyoftheturbine.Assumingthecoefficientofvelocityas
0.98
GIVEN:
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SOLUTION:
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Work done by Jet per Second:
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Hydraulic Efficiency:
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PROBLEM 2
APeltonwheelistobedesignedforthefollowingspecifications:
Shaftpower=11,772KW;head=380m;speed=750rpm,
Overallefficiency=86%.Jetdiameterisnottoexceedone-sixthofthe
wheeldiameter.Determinethe
i)Wheeldiameterii)Numberofjetsrequired
iii)Diameterofthejet.
GIVEN:
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SOLUTION:
Velocity of Jet:
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Velocity of Wheel:
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Wheel Diameter:
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Jet Diameter:
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Overall Efficiency:
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No of Jet:
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PROBLEM 3
APeltonturbineisrequiredtodevelop9000kWwhenworking
underaheadof300mtheimpellermayrotateat500rpm.
Assumingajetratioof10andoverallefficiencyof85%calculate
(i)Quantityofwaterrequired(ii)Diameterofthewheel(iii)
Numberofjets(iv)Numberandsizeofthebucketvanesonthe
runner
GIVEN:
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SOLUTION:
Velocity of Jet:
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Velocity of Wheel:
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Wheel Diameter:
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Jet Diameter:
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Overall Efficiency:
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No of Jet:
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Size of Bucket:
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Axial Width:
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Radial Length:
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Depth of Bucket:
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Number of Bucket:
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PROBLEM 4
APeltonwheelsuppliedwaterfromreservoirunderagrossheadof112m
andthefrictionlossesinpenstockamountsto20mofhead.Thewaterfrom
penstockisdischargedthroughasinglenozzleofdiameterof100mmatthe
rateof0.30m
3
/s.Mechanicallossesduetofrictionamountsto4.3kWof
powerandtheshaftpoweravailableis208kW.Determinevelocityofjet,
waterpoweratinlettorunner,powerlossesinnozzles,powerlostinrunner
duetohydraulicresistance.
GIVEN:
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SOLUTION:
Velocity of Jet:
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Velocity of Wheel:
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Power at Base of Nozzle:
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Power Loss in Nozzle:
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Power Loss in Runner:
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PROBLEM 5
APeltonturbinehaving1.6mbucketdiameterdevelopsa
powerof3600kWat400rpm,underanetheadof275m.Ifthe
overallefficiencyis88%,andthecoefficientofvelocityis0.97,
findspeedratio,discharge,diameterofthenozzleandspecific
speed.
GIVEN:
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SOLUTION:
Velocity of Jet:
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Velocity of Wheel:
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Speed Ratio
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Overall Efficiency:
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Diameter of Nozzle:
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Specific Speed :
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PROBLEM 6
APeltonwheelwhichisreceivingwaterfromapenstockwithagross
headof510m.One-thirdofGrossheadislostinthepenstock.Therate
offlowthroughthenozzlefittedattheendofthepenstockis2.2
m
3
/sec.Theangleofdeflectionofthejetis165°.Determine(1)The
powergivenbythewatertotherunner(2)Hydraulicefficiencyofthe
Peltonwheel.TakeC
v=1andspeedratio=0.45
GIVEN:
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SOLUTION:
Velocity of Jet:
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Velocity of Wheel:
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Total Head:
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Power given by Water to Runner
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Hydraulic Efficiency:
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PROBLEM 7
APeltonwheelishavingameanbucketdiameterof1mandis
runningat1000rpm.ThenetheadonthePeltonwheelis700
m.Ifthesideclearanceangleis15°andthedischargethrough
thenozzleis0.1m
3
/sec,findthei)poweravailableatthe
nozzleandii)hydraulicefficiencyoftheturbine.TakeC
V=1.
GIVEN:
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SOLUTION:
Velocity of Jet:
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Velocity of Wheel:
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Power available at Nozzle:
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Hydraulic Efficiency:
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PROBLEM 8
APeltonwheelissuppliedwithwaterunderaheadof35
mattherateof40.5kl/min.Thebucketdeflectsthejet
throughanangleof160°andthemeanbucketspeedis
13m/s.Calculatethepowerandhydraulicefficiencyofthe
turbine.
GIVEN:
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SOLUTION:
Velocity of Jet:
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Work done by Jet per Second:
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Hydraulic Efficiency:
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PROBLEM 9
AsinglejetPeltonwheelrunsat300rpmunderaheadof510
m.Thejetdiameteris200mmanditsdeflectioninsidethe
bucketis165°.Assumingthatitsrelativevelocityisreduced
by15%duetofriction,determine(i)waterpower(ii)
resultantforceonbucketand(iii)overallefficiency
GIVEN:
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SOLUTION:
Velocity of Jet:
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Discharge:
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Resultant Force:
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Shaft Power:
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Water Power:
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Overall Efficiency:
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PROBLEM 10
Consideranimpulsewheelwithapitchdiameterof2.75mand
abucketangleof170°.Ifthevelocityis58m/s,thejet
diameteris100mm,andtherotationalspeedis320rpm,find
theforceonthebuckets,thetorqueontherunner,andthe
powertransferredtotherunner.Assume�
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GIVEN:
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SOLUTION:
Velocity of Wheel:
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Discharge:
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Resultant Force:
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Shaft Power:
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Water Power:
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Overall Efficiency:
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PROBLEM 11
ThenozzleofaPeltonwheelgivesajetof9cmdiameterandvelocity
75m/s.Coefficientofvelocityis0.978.Thepitchcirclediameteris1.5m
andthedeflectionangleofthebucketsis170°.Thewheelvelocityis
0.46timesthejetvelocity.EstimatethespeedofthePeltonwheel
turbineinrpm,theoreticalpowerdevelopedandalsotheefficiencyof
theturbine.
GIVEN:
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SOLUTION:
Speed of Turbine:
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Velocity of Jet:
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Discharge:
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Theoretical Power:
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Overall Efficiency:
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THANK YOU