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1、华北电力大学硕士学位论文AbstractInrecentyears,duetothehighefficiencyandwideadjustmentrange,theaxialfanswithadjustablevanesarewidelyappliedinpowerplants.However,inactualoperation,becauseofdrasticchangesintheworkingenvironmentorself-regulationdelayinaxialfanswithadjustablevanes,flowphenomenasu
2、chasflowseparation,stall,surgeandbladedriftmayoccur.Thesecanleadtothedecreaseoftotalpressureandefficiency,andevencausetheequipmentdamageandaseriesofaccidents.Inthispaper,anaxialfanwithadjustablevanesofacertainpowerplantistakenastheresearchsubject.ByusingFluent,thesteadyandunstead
3、ysimulationsunderacertainbladeinstallationangleswereconducted.Andthe3Dflowfieldsbeforeandafterrotatingststallinthe1impellerwereanalyzed.Theresultsareasfollows:(1)Underthebladeinstallationangleof3°,rotatingstalloccursattheflowrateof373m/sintheaxialfan.Thestallinceptionshowsspikety
4、pewitharotatingspeedof0.667wr.Thenittakes2or3rotationcyclesforthestallinceptiontoturnintostallcellwitharotatingspeedof0.5wr.Duringtheoccurrenceanddevelopmentofthestallcell,alongwiththerotationoftheimpellers,theimpactareaofrotatingstallextendsalongthecircumferential,axialandradial
5、directions.Also,theflowfieldsandenergylosssituationintheimpellerchangecorrespondingly.(2)Meanwhile,theinfluenceofbladetipleakageflowonthestallinceptionisdiscussed.Atnearstallstage,thebladetipleakageflowgetsenhancedduetothedecreaseofflow,andtheleakagevortextrajectoryshowsatrendtom
6、ovetothebladeleadingedge.Whenitcomestothecriticalvalue,thebackflowrolledupbytheleakagevortexblocksthebladepassage,andgraduallydevelopsintostallcell.Whenthestreamlinesoftheflowmixedbytheleakageflowandmainstreamareparalleltothefrontallinesofthebladeleadingedge,thespikestallinceptio
7、nfirstcomesintobeing.Andthebackflowatthetrailingedgeandtheoverflowattheleadingedgeofthenextbladeindicatetheformationofstallcell.Keywords:axialfan;numericalsimulation;rotatingstall;stallinceptionII目录目录摘要..............................................................................
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