Abstract：Inthedesignofthecentrifugalfan,theneedtoconsiderthebodystructure,volumeflow,workingmediumtemperatureanddensity,andsometimesneedtotakeintoaccountsomespecialrequirementsandsoon.Therefore,weshouldfirstunderstandthecentrifugalfanofthegeneraldesignrequirements,inordertocarryoutareasonabledesign,toavoidmistakes.Therequirementsforcentrifugalfandesignaregenerally:meettherequiredflowandpressureconditionsshouldbeinthevicinityofthehighestefficiencypoint;thehighestefficiencyvalueshouldbeaslargeastheefficiencycurveflat;pressurecurvestableworkingrangetowide;fanstructureissimpleEasytooperateandeasytooperate,easytooperate,easytooperate,easytooperate,easytooperate,easytooperate,easytooperate,easytooperate,easytooperate,easytooperate,easytooperate,Easydisassemblyandtransportation.Infact,itisgenerallyimpossibletomeetalloftheaboverequirements,forexample,thereisoftenacontradictionbetweenaerodynamicperformanceandstructure(strength,process).Thesolutiontothecontradictionistoseizethemaincontradictionstocoordinatethesolution,whichrequiresdesignerstochooseareasonabledesign.Centrifugalfansusedifferentrequirementsarenotthesame,suchaspublicbuildingsusedincentrifugalfansaregenerallyusedforventilation,themostimportantrequirementisthelownoise,multi-wingcentrifugalfanwiththisfeature;andrequirelargeflowOfthecentrifugalfanisusuallydoublesuctiontype;forsomehigh-pressurecentrifugalfan,thanthelowspeed,therelativeproportionofitsleakagelossisgenerallylarger.Centrifugalfaninthedesignshouldpayattentiontothefollowing:(1)leafexitangleselection:leafexitangleisthedesignofthefirsttobeselectedoneofthemaingeometricparameters.Inordertofacilitatetheapplication,theleavesareusuallyclassifiedas:strongafterbendingtheblade,afterbendingthecircularblade,afterbendingstraightblade,afterbendingmachinewingblade;radialexitleaves,radialstraightblade.(2)reasonablechoiceofbladetype:commonfanatacertainspeed,theimpellertothesmallerpressurecoefficient,theimpellerdiameterislarger,anditshighefficiency;theoppositeistheoppositeoftheimpeller.(3)thechoiceofvolutesize:volutesizeshouldbeassmallaspossible.Forthehighthanthenumberofwindturbines,canbeusedtoshortenthescroll,thelowerthanthenumberofwindturbinesgenerallyusethestandardscroll.Sometimesinordertonarrowthevolutesize,optionalvoluteexportspeedisgreaterthanthefaninletspeedprogram,thistimeusingtheexportdiffusertoimproveitsstaticpressurevalue.(4)thechoiceofthenumberofleaves:Inthecentrifugalfan,increasingthenumberofleavesoftheimpellercanincreasethetheoreticalpressureoftheimpeller,becauseitcanreducetheimpactofrelativevortex.However,theincreaseinthenumberofbladeswillincreasethefrictionlossoftheimpellerchannel,whichwillreducetheactualpressureofthefanandincreasetheenergyconsumption.Thus,foreachimpeller,thereisanoptimalnumberofblades.Determinethenumberofleaves,sometimesbasedontheexperienceofthedesigner.(5)thechoiceoffullpressurecoefficient:thedesignofcentrifugalfan,theactualpressureisalwaysgiveninadvance.Atthistimeneedtoselectthefullpressurecoefficient.(6)thedeterminationofthemaingeometricdimensionsoftheimpellerinletandoutlet:theimpelleristheonlycomponentofthefan'senergydeliveredtothegas,soitsdesignhasagreatinfluenceonthefan;canthecorrectstructureoftheimpellerbedeterminedcorrectlyandtheperformanceparametersofthecentrifugalfanKeyrole.Itcontainsthekeytechnologyofcentrifugalfandesign-thedesignoftheblade.Thekeypartofthedesignofthebladeishowtodeterminethebladeexitangle.
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