为电力设计并研制三分之一比例的垂直轴风力发电机毕业论文外文翻译文档格式.docx
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为电力设计并研制三分之一比例的垂直轴风力发电机毕业论文外文翻译文档格式.docx
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DESIGNANDDEVELOPMENTOFA1/3SCALEVERTICAL
AXISWINDTURBINEFORELECTRICALPOWERG
Abstract:
ThisresearchdescribestheelectricalpowergenerationinMalaysiabythemeasurementofwindvelocityactingonthewindturbinetechnology.Theprimarypurposeofthemeasurementoverthe1/3scaledprototypeverticalaxiswindturbineforthewindvelocityistopredicttheperformanceoffullscaledH-typeverticalaxiswindturbine.Theelectricalpowerproducedbythewindturbineisinfluencedbyitstwomajorpart,windpowerandbeltpowertransmissionsystem.Thebladeandthedragareasystemareusedtodeterminethepowersofthewindthatcanbeconvertedintoelectricpoweraswellasthebeltpowertransmissionsystem.Inthisstudybothwindpowerandbeltpowertransmissionsystemhasbeenconsidered.Asetofbladeanddragdeviceshavebeendesignedforthe1/3scaledwindturbineattheThermalLaboratoryofFacultyofEngineering,UniversitiIndustriSelangor(UNISEL).Testhasbeencarriedoutonthewindturbinewiththedifferentwindvelocitiesof5.89m/s,6.08m/sand7.02m/s.Fromtheexperiment,thewindpowerhasbeencalculatedas132.19W,145.40Wand223.80W.Themaximumwindpowerisconsideredinthepresentstudy.
Keywords:
Beltpowertransmissionsystem;
Reynoldsnumber;
windpower;
windturbine
INTRODUCTIONWindenergyisthekineticenergyassociatedwiththemovementofatmosphericair.Ithasbeenusedforhundredsofyearsforsailing,grindinggrain,andforirrigation.Windenergysystemsconvertthiskineticenergytomoreusefulformsofpower.Windenergysystemsforirrigationandmillinghavebeeninusesinceancienttimesandsincethebeginningofthe20thcentury,itisbeingusedtogenerateelectricpower.Windmillsforwaterpumpinghavebeeninstalledinmanycountriesparticularlyintheruralareas.
Windturbineisamachinethatconvertsthewind'
skineticenergyintorotarymechanicalenergy,whichisthenusedtodowork.Inmoreadvancedmodels,therotationalenergyisconvertedintoelectricity,themostversatileformofenergy,byusingagenerator(Fitzwateretal.,1996).Forthousandsofyearspeoplehaveusedwindmillstopumpwaterorgrindgrain.Evenintothetwentiethcenturytall,slender,multi-vanedwindturbinesmadeentirelyofmetalwereusedinAmericanhomesandranchestopumpwaterintothehouse'
splumbingsystemorintothecattle'
swateringtrough.AfterWorldWarI,workwasbeguntodevelopwindturbinesthatcouldproduceelectricity.MarcellusJacobsinventedaprototypein1927thatcouldprovidepowerforaradioandafewlampsbutlittleelse.Whendemandforelectricityincreasedlater,Jacobs'
ssmallinadequatewindturbinesfelloutofuse.Thefirstlarge-scalewindturbinebuiltintheUnitedStateswasconceivedbyPalmerCosslettPutnamin1934;
hecompleteditin1941.Themachinewashuge.Thetowerwas36.6yards(33.5meters)high,anditstwostainlesssteelbladeshaddiametersof58yards(53meters).Putnam'
swindturbinecouldproduce1,250kilowattsofelectricity,orenoughtomeettheneedsofasmalltown(Monettetal.,1994).Itwas,however,abandonedin1945becauseofmechanicalfailure.Withthe1970soilembargo,theUnitedStatesbeganoncemoretoconsiderthefeasibilityofproducingcheapelectricityfromwindturbines.In1975theprototypeMod-Owasinoperation.Thiswasa100kilowattturbinewithtwo21-yard(19-meter)blades.Moreprototypesfollowed(Mod-OA,Mod-1,Mod-2,etc.),eachlargerandmorepowerfulthantheonebefore.
Currently,theUnitedStatesDepartmentofEnergyisaimingtogobeyond3,200kilowattspermachine.Manydifferentmodelsofwindturbinesexist,themoststrikingbeingthevertical-axisDarrieus,whichisshapedlikeaneggbeater(Fitzwateretal.,1996).Themodelmostsupportedbycommercialmanufacturers,however,isahorizontal-axisturbine,withacapacityofaround100kilowattsandthreebladesnotmorethan33yards(30meters)inlength.Windturbineswiththreebladesspinmoresmoothlyandareeasiertobalancethanthosewithtwoblades.Also,whilelargerwindturbinesproducemoreenergy,thesmallermodelsarelesslikelytoundergomajormechanicalfailure,andthusaremoreeconomicaltomaintain.WindfarmshavesprungupallovertheUnitedStates,mostnotablyinCalifornia.Windfarmsarehugearraysofwindturbinessetinareasoffavorablewindproduction.Agreatnumberofinterconnectedwindturbinesarenecessaryinordertoproduceenoughelectricitytomeettheneedsofasizablepopulation.Currently,17,000windturbinesonwindfarmsownedbyseveralwindenergycompaniesproduce3.7billionkilowatt-hoursofelectricityannually,enoughtomeettheenergyneedsof500,000homes.Awindturbineconsistsofthreebasicparts:
thetower,thenacelle,andtherotorblades.Thetoweriseitherasteellatticetowersimilartoelectricaltowersorasteeltubulartowerwithaninsideladdertothenacelle.Thefirststepinconstructingawindturbineiserectingthetower.Althoughthetower'
ssteelpartsaremanufacturedoffsiteinafactory,theyareusuallyassembledonsite.Thepartsareboltedtogetherbeforeerection,andthetoweriskepthorizontaluntilplacement.Acraneliftsthetowerintoposition,allboltsaretightened,andstabilityistesteduponcompletion.Next,thefiberglassnacelleisinstalled.Itsinnerworkingsmaindriveshaft,gearbox,andbladepitchandyawcontrolsareassembledmountedontoabaseframeatafactory(Hammons,2004).Thenacelleisthenboltedaroundtheequipment.Atthesite,thenacelleisliftedontothecompletedtowerandboltedintoplace.Inaddition,theaerodynamicsofawindturbineattherotorsurfaceisverymuchimportantinaerodynamicfields.Therotoraxisisbroughttoaverticalorientationwithawindvanemountedonacontrolshafttoorientatethebladeswithchangingwinddirection.Usingpitchregulationtherotorbladesturnaroundtheiraxissothattheaerodynamiccharacteristicsofthebladeandrotorarecontrolled.Therotorisyawoutofthewindwhichturnstherotorplanetofollowthechangingwinddirection.Thehubisconnectedtotherotorwithrigidboltconnectionandtherotationalspeedoftherotorisfixedrelativetothefrequencyofthegrid.Thefuturecanonlygetbetterforwindturbines.Thepotentialforwindenergyislargelyuntapped.ThetotalamountofelectricitythatcouldpotentiallybegeneratedfromwindintheUnitedStateshasbeenestimatedat10,777billionkWhannually(Keith,2005).Thesenewwindfarmsdemonstratehowwindenergycanhelptomeetthenation’sgrowingneedforaffordable,reliablepower.Withcontinuedgovernmentencouragementtoaccelerateitsdevelopment,thisincreasinglycompetitivesourceofrenewableenergywillprovideatleastsixpercentofthenation’selectricityby2020.Researchisnowbeingdonetoincreasetheknowledgeofwindresources.Thisinvolvesthetestingofmoreandmoreareasforthepossibilityofplacingwindfarmswherethewindisavailableandstrong.Plansareineffecttoincreasethelifespanofthemachinefromfiveyearsto20to30years,improvetheefficiencyoftheblades,providebettercontrols,developdrivetrainsthatlastlonger,andallowforbettersurgeprotectionandgrounding.TheUnitedStatesDepartmentofEnergyhasrecentlysetupascheduletoimplementthelatestresearchinordertobuildwindturbineswithahigherefficiencyratingthanisnowpossible(theefficiencyofanidealwindturbineis59.3percent(Milligan&
Artig,1999).Thatis,59.3percentofthewind’senergycanbecaptured.Turbinesinactualuseareabout30percentefficient).TheUnitedStatesDepartmentofEnergyhasalsocontractedthreecorporationstoinvestigatewaystoreducemechanicalfailure.Thisprojectbeganinthespringof1992andwillextendtotheendofthecentury.Windturbineswillbecomemoreprevalentinupcomingyears.Theturnofthecenturyshouldseewindturbinesthatareproperlyplaced,efficient,durable,andnumerous.Fromtheinvestigationofthiswindturbinebackground,anH-type,verticalaxiswindturbinehasbeendesignedandbuiltinthermalLaboratoryUniversitiIndustriSelangorthathasthecapabilitytoself-start.Inaddition,thisturbinehasbeendesignedtoallowavarietyofmodificationssuchasbladeprofileandpitchingtobetested.Thefirstpartofthedesignprocess,whichincludedresearch,brainstorming,engineeringanalysis,turbinedesignselection,andprototypetestinghavebeenincorporated.Usingdataobtainedthroughproperinvestigationresults,thefinalfull-scaleturbinehasbeendesignedandbuilt.Windturbinescanbeseparatedintotwotypesbasedbytheaxisinwhichtheturbinerotatesnamelyhorizontalaxiswindturbine(HAWT)andtheverticalaxiswindturbine(VAWT).HAWThasdifficultyoperatinginnearground,turbulentwindsbecausetheiryawandbladebearingneedsmoother,morelaminarwindflows,difficulttoinstallneedingverytallandexpensivecranesandskilledoperators,downwindvariantssufferfromfatigueandstructuralfailurecausedbytheturbulenceandheightcanbeasafetyhazardforlow-altitudeaircraft.Otherthanthat,theaerodynamicsofahorizontal-axiswindturbineiscomplex.Theairflowatthebladesisnotthesameastheairflowfarawayfromtheturbine.Theverynatureofthewayinwhichenergyisextractedfromtheairalsocausesairtobedeflectedbytheturbine.Inaddition,theaerodynamicsofawindturbineattherotorsurfaceincludeseffectsthatarerarelyseeninotheraerodynamicfields.AwidevarietyofVAWTconfigurationshavebeenproposed.TheDarrieusverticaltypewindturbineisth
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