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Analysisofenergylossesanditsmechanismsinacentrifugalimpeller
basedonmeanflowkineticenergytransport
1
1,2
CHENWeisheng,LIYaojun ,LIUZhuqing 1,2
(1.CollegeofWaterResourcesandCivilEngineering,ChinaAgriculturalUniversity,Beijing 100083,China;
2.BeijingEngineeringResearchCenterofSafetyandEnergySavingTechnologyforWaterSupplyNetworkSystem,
Beijing 100083,China)
Abstract:Energylossesintheimpellerarethekeyfactorsaffectingthehydraulicperformanceofcentrifugalpump.
Inthispaper,theVeryLargeEddySimulation(VLES)turbulencemodelwhichdirectlyresolvesthelarge - scale
turbulencestructureisusedtonumericallysimulatetheinternalflowofalowspecificspeedcentrifugalimpellerat
threeflowrates(1.0Q d ,0.6Q d and0.25Q d ),aimtorevealthemeanflowkineticenergylosscharacteristicsinthe
impeller.Apowerlossanalysismethodbasedonthetransportofmeanflowkineticenergyisproposedandapplied
tostudytheinternalflowfeatures ,energylossesanditsmechanismoftheimpeller.Thenewlyproposedpowerloss
analysismodelcalculatesthedirectviscouslossesandtheturbulentenergyproductionbyintegratingthedirectvis
cousdissipationtermandtheturbulentkineticenergyproductiontermofthemeanflowkineticenergytransporte
quation ,establishesthecorrelationbetweenflowcharacteristicswithmeanflowkineticenergyloss,andobtainsthe
spatialdistributionofmeanflowkineticenergylossesintheflow.Theresultsshowthatthedirectviscouslossesof
theimpellerareconcentratedinthenear - wallregionanddecreasessignificantlywiththedecreaseofflowrate.The
strongsheareffectresultedbythecomplexflowstructureintheturbulentcoreregionoftheimpelleristhedirect
causefortransferofenergyfromthemeanflowtotheturbulentstructures.However ,differencesarefoundinthe
mechanismofturbulentkineticenergyproductionfordifferentflowstructures.Inthestrongshearflowregionformed
,
bythebladepressuresideseparationflow ,theturbulentkineticenergyproductionterm componentsP andP r θ
θθ
promotingenergytransportfromthemeanflowtotheturbulentstructure,increasingthecircumferentialandradial
componentsofturbulentkineticenergy ,whileP rr reducestheradialcomponentofturbulentkineticenergyandsup
pressesthemeankineticenergylosses.Fortheshearflowcausedbybladesuctionsideseparationflowsandinthe
andP rr arethedominantfactorsforturbulentkineticenergyproduction,andP sup
impelleroutletbackflow ,P r θ
θθ
pressesthegenerationofturbulentkineticenergy.
Keywords:centrifugalimpeller;meanflow kineticenergy;turbulentkineticenergy;energyloss;verylarge
eddysimulation
(责任编辑:王 婧)
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