燃气轮机计算

ME423Chapter8PREDICTIONOFPERFORMANCEOFSIMPLEGASTURBINESProf.Dr.O.CahitERALPPredictionofPerformanceforGTMe423Spring2006Prof.Dr.O.CahitERALP•FromcyclecalculationsitispossibletodeterminethePRESSURERATIO(Rc)whichwillgivethebestoverallefficiencyforagivenTmax.•MASSFLOWRATEtogivethemostsuitabledesiredpoweroutput.•Aftersuchpreliminarycalculations,themostsuitabledesigndataforaparticularapplicationcanbechosen.•Then,itispossibletodesignindividualcomponentstogivetherequiredoperationatthedesignpoint.•ThatisrunningatthedesignspeedN*,massflowratem*andpressureratioR*.PredictionofPerformanceofSimpleGasTurbine()mPredictionofPerformanceforGTMe423Spring2006Prof.Dr.O.CahitERALP•Thentheoff-designperformancehastobedeterminedwhichisthedivergencefromthedesignpointoverthecompleteoperatingrangeofspeedandpoweroutput.•Theperformance¢oftheindividualcomponentsmaybeestimatedonthebasisofthepreviousexperienceoractualexperiments.Whentheyarecombinedinanenginetheiroperatingrangeisconsiderablyreduced.•TheproblemistofindtheOperatingpoint(OP)oneachcomponent¢whentheengineisrunningatasteadyspeed(EQUILIBRIUM).•TheplotoftheseOP'sformtheEQUILIBRIUMRUNNINGLINE(ERL).PredictionofTerformanceofSimpleGasTurbinePredictionofPerformanceforGTMe423Spring2006Prof.Dr.O.CahitERALP•Forthewholerangeofoperatingspeeds,itwillgeneratetheEQUILIBRIUMRUNNINGDIAGRAM.•DeterminingtheOP;thepoweroutput,thrustandtheSFCcanbeobtained.•TheEquilibriumRunningDiagramindicatesthemarginofoperationfromthesurgeline(SL).•ThismarginindicatesaMarginofstability;indicatesifthereisenoughmargintooperatewithadequatecompressorefficiency.•Ifthesurgelineiscrossedsomeactionhastobetakentorecover,nottogiverisetoafailure.•Ideallytheengineshouldbeoperatedwithintheregionofmaximumpossibleefficiencies.PredictionofPerformanceofSimpleGasTurbinePredictionofPerformanceforGTMe423Spring2006Prof.Dr.O.CahitERALP•VariationofSFCwithreductioninpowerPARTLOADPERFORMANCE.ThisisimportantwhilerunningtheGTatlowpowersettings.•PoorsfcatpartloadisthebiggestdisadvantageofaGT,especiallyavehicularone.•Theeffectofambientconditionsonmaximumoutputisalsoimportant,i.e.high&lowTaandPa.•Peakloadenergygeneration:Europe:colddaysinwinter,America:hotdaysinSummerforairplanes:Runwaylength(safety)andpayload(economics)areaffected.PredictionofPerformanceofSimpleGasTurbinePredictionofPerformanceforGTMe423Spring2006Prof.Dr.O.CahitERALPOff-DesignPerformanceofSimpleGT•Herewewilltrytoanalysea:a)Singleshaftunitdeliveringshaftpower.b)Freeturbineengine-powerturbinedrivestheload.c)Simplejetengine,wheretheusefuloutputisfromthepropellingnozzle.•Morecomplexarrangements-twospoolengines,Turbofan&transientperformanceChapter9•FlowcharacteristicsofafreeturbineandpropellingnozzlearesimilarandimposethesamerestrictionsontheGasGenerator.•AsaresultofthisseveraljetengineshavebeenconvertedtoFreeTurbinePowerengineforpeakloadelectricgeneration,andmarineapplications.PredictionofPerformanceforGTMe423Spring2006Prof.Dr.O.CahitERALPComponentCharacteristics¢FIG.1CompressorCharacteristics•Axialcompressor¢constantspeedlinesbecomeverticalsoηc,Rcvsisplotted.mPredictionofPerformanceforGTMe423Spring2006Prof.Dr.O.CahitERALPComponentCharacteristics¢FIG.2TurbineCharacteristics•Turbine¢donotshowasignificantvariationinNDspeed.Theiroperatingrangeisusuallyseverelyrestrictedbyanothercomponentdownstream.PredictionofPerformanceforGTMe423Spring2006Prof.Dr.O.CahitERALP•Sinceinletandexhaustpressurelossesareignored;pressureratioacrosstheturbineisdeterminedbythecompressorpressureratioandthepressurelossinthecombustionchamber;ΔP034=P012-P032•Themassflowthroughtheturbine=massflowthroughthecompressor-Bleeds+fuelflow;Off-DesignOperationofTheSingle-ShaftGT31bleedfmm-m+mPredictionofPerformanceforGTMe423Spring2006Prof.Dr.O.CahitERALPa)SelectaconstantspeedlineontheC¢andchooseanOPonthislinethusN/T01areselected.b)ThecorrespondingpointontheT¢isobtainedbytheCompatibilityofSpeedandFlow.•COMPATIBILITYOFROTATIONALSPEEDProcedureofObtaininganEquilibriumRunningPoint01030301N=TTNTT.0101c0102P;;PmTPPredictionofPerformanceforGTMe423Spring2006Prof.Dr.O.CahitERALP•COMPATIBILITYOFFLOW•HerecombustionchamberpressurelossP03/P02=1-Pb/P02•assumeProcedureofObtaininganEquilibriumRunningPoint...3031010102033.03010203011mmPPm=****PPmTTTPPT..03010102030301020301mmPPT=xxPPTTTPP...13mmmPredictionofPerformanceforGTMe423Spring2006Prof.Dr.O.CahitERALPProcedureofObtaininganEquilibriumRunningPoint.0101mTParefixedbythechosenOPontheisassumedtobeconstant.NeglectinginletandexhaustpressurelossesPa=P01=P04isafunctionofPP0201and0302PP.03030304mPPTPPP0304=PPPP03020201.C?PredictionofPerformanceforGTMe423Spring2006Prof.Dr.O.CahitERALPProcedureofObtaininganEquilibriumRunningPointNowintheflowcompatibilitytheonlyunknownisTherestcanbeobtainedfromC¢andT¢.Thus,Thus,knowingT01,T03canbecalculated.TT0301/.0303030203.0101020101mTPPP=()..PPmTPTTPredictionofPerformanceforGTMe423Spring2006Prof.Dr.O.CahitERALPProcedureofObtaininganEquilibriumRunningPoint•HavingdeterminedT03,theSPEEDCOMPATIBILITY:•Thecompressor&turbinetemperaturechangescanbedetermined.