IntroductiontoRotorDynamicsproventobeagoodmeanstoaddadditionaldampingtotherotorsystemtoimprovestability.Inprinciple,thedampersealislikeasilencerforagun.Ithasradialholeswhich“trap”thegasesandproducesmall“pocketsofdamping”.Thesetechnologieshavebeenputtogooduseintherecentyearsandhavereducedthenumberofstabilityproblemsintheturbomachineryindustry.?Swirlbrakes:Thecauseforaero-inducedexcitingforces,asnotedabove,istheswirlorthetangentialvelocitycomponentofthegas.Ifweareabletoredirectthegastoreducetheswirlvelocity,wecouldpotentiallyreducetheexcitationforces.Theswirlbrakeisastationaryringwithblade-likeaxial“teeth”alongitscircumference.Theteethredirectthegasflowandreducetheswirlvelocity.Thisdeviceimprovesthestabilityoftherotor-bearingsystem.Itisusedattheimpellereyesealsandatthebalancepistonordivisionwallsealofacentrifugalcompressor.Shuntholes:Similartoswirlbrakes,takinggasoffthediffuserofthelaststageimpellerandinjectingitbeforethebalancepistonordivisionwallwillalsoreducetheswirlvelocity.Theyaretypicallyusedatthedivisionwallofaback-to-backcompressor.?AcknowledgementTheinformationcontainedinthispresentationconsistsoffactualdataandtechnicalinterpretationsandopinionswhich,whilebelievedtobeaccurate,isofferedsolelyforinformationpurposes.Norepresentationorwarrantyismadeconcerningtheaccuracyofsuchdata,interpretationsandopinions.ShortCourseatGMRC2005Page21of23IntroductiontoRotorDynamics7.0References:1.Kirk,R.G.,1980,“StabilityandDampedCriticalSpeeds:HowtoCalculateandInterprettheResults,”CAGITechnicalDIGEST,Vol.12,No.2,pp.375-3832.Ruddy,A.V.,andSummers-Smith,D.,1980,“AnIntroductiontotheinfluenceofthebearingsonthedynamicsofrotatingmachinery”,TribologyInternational,October.3.White,D.C.,1972,“TheDynamicsofRigidRotorSupportedonSqueezeFilmBearings,”I.Mech.E.,ConferenceonVibrationinRotatingSystems,pp.213-229.4.APIStandard6177thEdition,July2002,“AxialandCentrifugalCompressorsandExpandercompressorsforPetroleum,ChemicalandGasIndustryServices”5.Memmott,E.A.,2002,“LateralRotordynamicStabilityCriteriaforCentrifugalCompressors,”CMVA,Proceedingsofthe20thMachineryDynamicsSeminar,QuebecCity,pp.6.23-6.32,October21-236.Memmott,E.A.,2000,“EmpiricalEstimationofaLoadRelatedCross-CoupledStiffnessandTheLateralStabilityOfCentrifugalCompressors,”CMVA,Proceedingsofthe18thMachineryDynamicsSeminar,Halifax,pp.9-20,April26-28.7.Wachel,J.C.andvonNimitz,W.W.,1981,"EnsuringtheReliabilityofOffshoreGasCompressorSystems,"JournalofPetroleumTechnology,pp.2252-2260,Nov.8.Alford,J.S.,1965,"ProtectingTurbomachineryfromSelf-ExcitedWhirl,"ASMEJournalofEngineeringforPower,Vol.38,pp.333-3449.Memmott,E.A.,1992,"StabilityofCentrifugalCompressorsbyApplicationsofTiltPadSeals,DamperBearings,andShuntHoles,"IMechE,5thInternationalConferenceonVibrationsinRotatingMachinery,Bath,pp.99-106,September7-10.10.Marshall,D.F.,Hustak,J.F.,andMemmott,E.A.,1993,"EliminationofSubsynchronousVibrationProblemsinaCentrifugalCompressorbytheApplicationofDamperBearings,TiltingPadSeals,andShuntHoles,"NJIT-ASME-HI-STLE,RotatingMachineryConferenceandExposition,Somerset,NewJersey,November10-12.11.Memmott,E.A.,1994,"StabilityofaHighPressureCentrifugalCompressorThroughApplicationofShuntHolesandaHoneycombLabyrinth,"CMVA,13thMachineryDynamicsSeminar,Toronto,Canada,pp.211-233,September12-13.12.Kuzdzal,M.J.andHustak,J.F.,1996,"SqueezeFilmDamperBearingExperimentalvs.AnalyticalResultsforVariousDamperConfigurations,"ProceedingsoftheTwentyFifthTurbomachinerySymposium,TurbomachineryLaboratory,DepartmentofMechanicalEngineering,TexasA&MUniversity,CollegeStation,Texas,September17-19.13.Ramesh,KandKirk,R.G.,1999,“NonlinearResponseofRotorsSupportedonSqueezeFilmDampers,”ProceedingsofDETC99–17thBiennialASMEVibrationsConference,ASMEPaperDETC99/VIB-8294,LasVegas,Nevada,September12-15ShortCourseatGMRC2005Page22of23IntroductiontoRotorDynamics14.Moore,J.J.andHill,D.L.,2000,“DesignofSwirlBrakesforHighPressureCentrifugalCompressorsUsingCFDTechniques,”8thInternationalSymposiumonTransportPhenomenaandRotatingMachinery,ISROMAC-8,Vol.II,Honolulu,Hawaii,pp.1124-1132,March26-3015.Ramesh,K,2002,"AState-of-the-artRotorDynamicAnalysisProgram,"Proceedingsofthe9thInternationalSymposiumonTransportPhenomenaandDynamicsofRotatingMachinery,Honolulu,Hawaii,February10-1416.Moore,J.J,Walker,S.T.,Kuzdzal,M.J.,2002,“RotordynamicStabilityMeasurementDuringFull-Load,Full-PressureTestingofa6000PSERe-InjectionCentrifugal”,32ndTurboMachinerySymposium,Houston,TX.17.Moore,J.J.andSoulas,T.A.,2003,“DamperSealComparisoninaHighPressureReInjectionCentrifugalCompressorDuringFull-Load,Full-PressureTestingUsingDirectRotordynamicStabilityMeasurement,”ASME,Proceedingsofthe19thBiennialConferenceonMechanicalVibrationandNoise,International2003DETC,Chicago,Illinois,DETC2003/VIB48458,September2-6ShortCourseatGMRC2005Page23of23
