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.docx

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.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

外文资料

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