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1、2000InternationalCompressorEngineeringConferenceatPurdue,PurdueUniversity,WestLafayette,Indiana,25-28July2000THECFDANALYSISOFASCREWCOMPRESSORSUCTIONFLOWA.Kovacevic,N.StosicandI.K.SmithCentreforPositiveDisplacementCompressorTechnology,CityUniversity,LondonEC1VOHB,U.K,n.stosi
2、c@city.ac.uk,www.city.ac.uk/staff/~sj376ABSTRACTDynamicflowlossesinthesuctionchamberplayaveryimportantifnotthemainroleintheefficiencydecreaseinscrewcompressors.Thedesignofthesemachines,togetherwiththeaccountingofflowlossesandhowtoreducethem,isstillbasedonlyonthesimpleanalys
3、is.SinceComputationalFluidMechanicsofferstodayamoreaccurateestimationofthevelocity,pressure,temperatureandconcentrationfieldswithinthescrewcompressor,suchstudiescanbethusextendedtodesignasuctionportwiththeminimizedflowlosses.ThispaperpresentsapplicationofaCFDproceduretocalc
4、ulateascrewcompressorsuctionflow.Thenumericalgridofasuctionchamberisgeneratedbya2-Dtransfiniteinterpolationcombinedwiththelayermeshingtechniquebothfacilitatedbyuseofanindependentandstand-aloneinterfaceprogramwhichconnectsascrewcompressorgeometrywithaconventionalnumericalpre
5、-processor.Thecalculationisappliedtotheoil-floodedscrewcompressorandobtainedwithComet,acommercialCFDsolver.INTRODUCTIONTheperformanceofscrewcompressorsmaybepredictedreasonablywellandfurtherperformanceimprovementscanbemadeeitherinoilinjectedoroilfreetypesofmachinesbyuseofafl
6、owsimulationmodelsbasedonComputationalFluidDynamics(CFD).ThereisalargenumberofpublicationsintheCFDfield,suchasthoseofDemirdzicandPeric,1990,Demirdzicetal,1993andFerzigerandPeric,1996.However,onlyseveralpapershavebeenpublishedontheuseofthistechniquefortheanalysisofflowthroug
7、hscrewcompressors,forexample,byStosicetal,1996andKovacevicetal,1999.Thisismainlyduetothecomplexityofbothgeometricconfigurationandtheflowthroughscrewcompressors.Themagnitudeofscrewcompressordimensionsvariesfromseveralcentimetresforthecompressionchambertofewmicrometersforthec
8、learances.Thereforeasuitablenumericalgridmustbegenerated,whichnotonlyaccuratelydes