航空活塞发动机涡轮增压介绍

TurbochargedSR22 SystemDescription TurboLimitations NormalOperatingProcedures EmergencyOperatingProceduresRevised2/14/07Turbonormalizevs.Turbocharged Aturbochargedenginehasboostedmanifoldpressureaboveambientsealevelpressure,increasingtheamountofpowertheengineiscapableofproducing.VS Aturbonormalizedenginecompensatesforthelossofambientsealevelpressureastheaircraft’saltitudeincreases.Thisallowstheenginetomaintainsealevelratedhorsepoweruptoveryhighaltitudes.Itdoesnotincreasetheamountofhorsepowertheengineiscapableofproducing.KeepinMind Theenginealwaysthinksitisatsealevel TheturbodoesNOTincreasetheratedhorsepoweroftheengineSystemComponentsUpperdeck Theportionoftheturbosystemthatstartsaftertheturbo/compressorandendsatthethrottleplate Theturbowillcreategreaterthansealevelpressureintheupperdeckbeforetheintercoolers KeyUpperdeckcomponents Intercooler OverboostcontrolIntercooler Theinductionairfromtheturboiswarmandpressurizedtoapproximately33inchesofpressure Theintercoolercoolstheinductionairforcombustionandreducespressureto29.6inchesOverboostprotection Intheeventofanoverboostconditionexcesspressurewillberelievedbytheoverboostpoppetvalve. Anoverboostcouldbecauseby: Excessiveoilpressureduetolowoiltemperature Malfunctionintheturbosystem(absolutepressurecontrolorwastegate)Turbo Turbo-usesacceleratedexhaustgasestospinacompressorwhichincreasesthepressureintheupperdeck. Capableof+100,000RPM MaximumTurboInletTemperature(TIT)is1750°F,seenonMFDEnginepage Turboislubricatedviatheengineoilsystem.CompressorTurboTurbo… Ascavengerpumpisaddedtopulloilthroughtheturboforcoolingandlubrication.Turbo…TwinTurbossupplypressuretotheupperdeckTurbo… Theturboallowstheenginetomaintain100%powerupto25,000’MSL. Themaximumcertificationaltitudeof25,000’MSLislowerthenthecriticalaltitude. Criticalaltitudeisthealtitudewheretheturbocanlowlongermaintainsealevelpressure.NotafactorintheCirrus Theamountofpressureproducedbytheturboisafunctionofexhaustallowedtoflowthroughtheturbo.Wastegate Thewastegatecontrolstheamountexhaustthatisallowedtoflowthroughtheturbo. Airwilltakethepathofleastresistance. Aclosedwastegatesendsmoreexhaustthroughtheturbo. AnopenedwastegateallowsExhausttobypasstheturboandbedumpedoverboard. Aspringholdsthewastegateintheopenposition.Oilpressureclosesthewastegate. Eachturbohasaninterconnectedwastegate.Wastegate…TrueorFalse?Anopenwastegatesendsmoreairthroughtheturbo.FALSEWastegateActuatorAbsolutePressureControl Movesthewastegatetomanagethepressurecreatedbytheturbo. Adjuststhewastegatetomaintainapproximatelysealevelpressureintheupperdeck Usesengineoilashydraulicfluidtomovewastegate.AbsolutePressureControl… Pressurefromtheupperdeckisplumbedintotheabsolutepressurecontrolunit. AnaneroidinsidetheAPCwillexpandandcontractbasedonthepressureintheupperdeck. Oilpressuretothewastegatecontrollerisadjustedbythemovementoftheaneroid. Whentheupperdeckpressuredropstheaneroidexpandsallowingoilpressuretoclosethewastegatesendingmoreexhaustthroughtheturbo.AirIntake Inductionairpassesthroughanairfilterinthefrontrightcowl. TheairflowsplitsaftertheairfiltertotherightandleftcompressorAirIntake Anautomaticalternateairsourcewillopeniftheairfilterbecomesclogged(ice,dirt…) Magnetsholdalternatedoorclosed.Whenthefilterclogsthepressuredropsintheintakeforcingthedooropen. Thedoorwillautomaticallyclosewhentheresistanceisgone. AmessagewillappearontheMFDalertingthepilotwhenthealternateairdooropensorcloses.FuelInjectors GAMIInjectorsareincludedwiththeturbokit. Tunedinjectorssupplyclosefuel/airratiostoallcylinders,importantforrunningleanofpeak PressurefromtheUpperdeckisplumbedtoeachinjectorpreventingthebackflowoffuelthroughtheinjectorathighaltitude.EngineDrivenFuelPump Upperdeckpressureisplumbedtoananeroidintheenginedrivenfuelpumpcontrollingtheamountoffuelthatgoestotheengineorreturnline. Highupperdeckpressurewillcausetheaneroidtocontractandincreasetheamountoffuelavailabletotheengine. Lowupperdeckpressurewillcausetheaneroidtoexpandedsendingmorefueltothereturnline. Whyisthisimportant?Whatwouldhappenifyouranatankdryathighaltitude.Magnetos Magnetosreceivepressurefromtheupperdecktopreventarcing AninlinefilterremovescontaminationandmoisturebeforetheairentersthemagnetoEnvironmental WarmpressurizedairistakenfromUpperdeckbeforetheIntercooler. Theairisplumbedthroughtheexhausttoincreasetemperature. Theairpressurefromtheupperdeckishigherthenthepressureintheexhaust.ThisreducesthechanceofCarbonMonoxidefromenteringthecabinfromanexhaustleak.Environmental… Avalveusesambientpressureandupperdeckpressuretocontroltheamountofhotairavailablefortheheater.PuttingitallTogetherEngineIdlingontheGroundatSeaLevel Isthewastegateopenorclosed? Why? Seespeakernotesfortheanswer.Thewastegateisopen.TheAbsolutePressureControllerwillpositionthewastegatetomaintain29.6inchesofmercuryintheupperdeck,measuredaftertheintercoolers.Theambientpressureatsealevelistypicallyclosetoorabove29.6inchesofmercury.Sincethepressureintheupperdeckisthesameasambientpressureandabove29.6,boostfromtheturbo/compressorisnotnecessary.FullThrottleatSeaLevel Isthewastegateopenorclosed? Why? Whatcouldcauseanoverboostwhenaddingtakeoffpower?Seespeakernotesfortheanswer.Wastegateisopen.Boostfromtheturbo/compressorisnotnecessaryatsealevelbecausethepressureintheupperdeckisatorabove29.6.DepartingDenverInternational(TrueofFalse) Themixtureshouldbeleanedfortakeofftocompensateforthehigheraltitude False!!!Seespeakernotesfortheanswer.Theturbo/compressorwillboostthepressureintheupperdecktocompensateforthedecreaseinpressureathigheraltitudes.Fuelflowwillbeconstantregardlessofaltitudetomatchtheconstantmanifoldpressuregoingintotheengine.AstheAircraftClimbsThrough: 5,000MSL 10,000MSL 15,000MSL 20,000MSL 25,000MSL Whathappenstothewastegate? Willthewastegatebefullyclosedat25,000MSL? Seespeakernotesfortheanswer.Astheaircraftclimbsthroughaltitudetheambientpressuredecreases.Theabsolutepressurecontrollersensesthedecreaseinpressureintheupperdeckandautomaticallyregulatesoilpressuretoclosethewastegatetoincreasetheamountofexhaustgoingthroughtheturbo.Theturbospinsfasterasaresultoftheincreaseinexhaust,whichspinsthecompressorfastertocompensateforthedecreaseinpressure.Theentireprocesshappensautomaticallyinacontinuouscycle.Thealtitudewherethewastegateiscompletelyclosedisreferredtoasthecriticalaltitude.Meaningtheturboisworkingashardasitcantocompensateforthedecreaseinatmosphericpressure.ThemaximumcertifiedaltitudeoftheturbochargedSR22is25,000.TheturbosystemiscapableofmaintainingsealevelratedpressureuptoandpossiblyaboveFL250.Sincethemaximumaltitudetheturboaircraftcanflyatisrestrictedbycertification,notaircraftperformance,wedonotknowwherethecriticalaltitudeis.Shortanswer-thewastegateisnotfullyclosedatFL250TurboLimitationsSystemLimitations OperatingLimitations Note:VnoandVnecanbeinterpolatedforaltitudesbetween17,500and25,000.ThePFDairspeedtapewillchangewithaltitudetoreflectthedifferenceinVne/VnoSystemLimitations AltitudeLimits MaximumTakeoffAltitude…...………..10,000MSL MaximumOperatingAltitude................25,000MSLNote:FAR91.211requirestheuseofoxygenbelowthemaximumoperatingaltitude. EnvironmentalConditions Donotoperatetheaircraftbelowanoutsideairtemperatureof-40°CSystemLimitations FlapLimitation Donotuseflapsabove………………...17,500MSL PowerPlant Avoidcontinuousoperationwiththefuelflowsetbetween30gphand18gphwiththeMPabove26’’MP Warning:ContinuousoperationwithMPabove26’’andfuelflowsetbetween30gphand18gphcouldleadtoenginedamageandpossiblefailure.Operationinthisareacanleadtoexcessivelyhighcylinderheadpressuresandtemperatures.NormalOperatingProceduresPreflight O2preflight O2quantity,requirementsanddurationtables VerifyO2flowtoeachmask/cannulathatwillbeused PulseOximeter Checksaturationlevelsonthegroundandmonitorduringflight. AdjustO2flowtomaintainsaturationlevelsabove90% CannulascannotbeusedaboveFL180asperFARpart23.MasksmustbewornaboveFL180.Planaccordingly. O2Considerations DonotusecannulasaboveFL180 PassengersshouldbethoroughlybriefontheuseofO2including: Properuseofmasks/cannulasandflowregulators Recognitionandresponsetohypoxia Recognitionandresponsetopilotincapacitation Ifsaturationlevelsdecreasebelow90% IncreasetoflowofO2 Increasemasksealaroundface Descendtoaloweraltitudeifsaturationlevelcannotbemaintainedabove90%NormalProcedures EngineStart NoChange Taxi LeanmixturetotheXinmiXture BeforeTakeoff NoChange Ensureoiltemperatureisabove100°Fbeforerunup Takeoff Fullthrottle Fullmixture(foreveryaltitude) Boostpumpon MonitorMPforoverboost IftheMPexceeds32inchesreducethethrottlebelow32inchesofMPNote:Manifoldpressureintheyellowarc(29.6–32)isnormalwithfullpowerandnoactionisrequiredaslongasMPdoesnotexceed32”FullPowerClimb Fullpower Mixturerichforallaltitudes Booston CHTcoolingisafunctionofairspeed CHT’sshouldbekeptwithinnormaloperatingtemperatures Cruiseclimbairspeeds Upto7000MSL-120KIAS After7000MSL–130KIAS LeanofPeakClimbAftertransitioningtoacruiseclimb Throttle2700RPM’s/MaxMP(fullthrottle) Mixtureleanto17.5GPH Boostpumpon Airspeed130KIASNote:CHT’sshouldbekeptbelow380°Fduringleanofpeakclimbs CHTcoolingisafunctionoffuelflowandairflow IFCHT’sexceed380°F Increaseairspeedandsacrificeclimbperformanceand/or Decreasefuelflow.5GPHatatime.CHT’sdonotrespondasquicklyasEGTs.MonitorCHT’sandwatchfortrends.Thiswillalsosacrificeclimbperformance. IfCHT’scannotmaintainedbelow380°Fwiththefuelflowandorairspeedswitchtoafullrichclimbsetting. Above18,000MSLtransitiontofullpower/fullmixtureclimb.OperationsLeanofPeak(EGT)EGT-exhaustgastempCHT-cylinderheadtempICP-internalcylinderpressureHP-horsepower1/BSFC-brakespecificfuelconsumption(efficiencyratingcomparingHPtofuelflow)Note: CloserelationshipofCHT,ICP,HP Orderofpeaks-HP,ICP,CHT,EGT Curvatureofpeaksontherichandleansideofpeak Richofpeak LeanerincreasesCHT Leanofpeak LeanerdecreasesCHTFullPowerClimbvs.LeanofPeakClimbsThefollowingisacomparisonbetweenaleanofpeakclimbandfullpowerclimbfromsealevelFullPowerClimbvs.LeanofPeakClimbsConsiderthefollowingfactorswhendecidingtoclimbLOPorROP WorkloadassociatedwithLOPclimbs CloselymonitorCHT’s Adjustingmixture/airspeedforcooling TransitioningtoROP@18,000MSL… Decreaseinclimbperformance Significanceoffuelsavings SignificanceofextrarangeCruise Leavepower,mixtureandboostuntilaircraftacceleratestocruisespeed Allcruisepowersettingswillbeleanofpeak Powersettingcanvaryfrom85%-65%fornormalcruiseandshouldbeselectedconsideringfuelandtimerequirements. TheMaxPowerFuelFlowplacardwillbereplacedwith: Avoidcontinuousoperationwiththefuelflowsetbetween18gphand30gphwiththeMPabove26”SettingCruisePower Throttleto2500RPM/MaxMP(29.0–29.6) Adjustmixtureto17.6–17.0GPH Mixtureshouldbepulledsmoothlyandpromptlyto17.5GPH.Smalladjustmentscanbemadeoncethefuelflowiswithintheballparkrange Percentpowerwillbeapproximately85% Reducethrottleto75%or65%asdesired IfCHT’sgoabove380°FduringlevelcruiseleanthemixturetocooltheCHT’s Ontheleansideofpeakapproximately.5gphleanernear380°Fshouldresultina15°FdecreaseinCHT. Boostpumpoffafter30Min.Why? Turningtheboostpumpoffwillchangefuelflows Beforeturningpumpoffnotefuelflow TurnboostpumpoffandreadjustmixturetopreviousfuelflowBoostPumpOperation Pressureaffectsthetemperaturerequiredtovaporizefuel Lowerpressure=lowervaporizationtemperature Lowboostprovidesextrapressuretokeepfuelfromvaporizingathighaltitude HighboostmaybenecessaryaboveFL180withwarmorhotfuelifvaporlockispresent Vaporlockcanberecognizedinflightby: Fluctuationsinnormalfuelflow RisingEGTsandTITcoupledwithfallingfuelflow RisingCHTsEngineRoughnessatLeanofPeak Unbalancedfuel/airratios Moreapparentduringleanofpeakoperations Why?,RemembertheHPcurveinrelationthefuel/airratiosUnbalancedFuel/AirratiosBalancedFuel/AirratiosDescent Descentplanningiskeywhenoperatingathigheraltitudes GarminVNAV Calculatetopofdescent(TOD) Altitudetoloose/1000fpm=TODETE Example;19,000’toloose/1000fpm=TOD19minuteETE Avoidpoweridleforextendedperiods MaintainCHT’sabove240°F(airspeed/powersetting) Throttle-reduceasnecessary Mixture-donottouch Boostpump-offNormalProcedures BeforeLanding Powerasrequired Flaps100% Mixturefullrich(regardlessoffieldelevation) BeforeFAFortrafficpattern Boostpumpon LightsasrequiredAfterLandingandShutdown AfterLanding Leanaircraftfortaxi Shutdown Nochange Turbocooldowntimeisnotrequired TurbocoolingisafunctionofoiltemperaturenotturboinlettemperatureTrueorFalse? LeaningtheenginewillcausetheCHT’storisewhenoperatingleanofpeak. Seespeakernotesforanswer.False,CHT’scoolapproximately15°F/.5gphwhenCHT’sarecloseto380°FScenarioDuringaleanofpeakclimbwhileclimbingat130KIAStheCHT’sexceed380°F Whatistheappropriateresponse? Whatifthatdoesnotwork? Whatifthatdoesnotwork? Seespeakernotesforanswer3optionsareavailabletokeepCHTsbelow380°Fduringaleanofpeakclimb.Increaseairspeed,whichwillincreasetheamountofairflowaroundthecylindersandsacrificeclimbperformanceDecreasefuelflow.DecreasingfuelflowwillhaveacoolingaffectontheCHTswhenoperatingLOP.DecreasingfuelflowwillalsosacrificepowerandclimbperformanceSwitchtoaROPclimbScenarioAftersettingcruisepowerat85%(2500RPM/MaxMPand17.6GPH)theCHT’sremainat395°F. Whatistheappropriateaction? SeespeakernotesforanswerAreductioninfuelflowwhenoperatingLOPwillhaveacoolingaffectontheCHTs.Tryleaningfuelflowapproximately.3GPH.GiveCHTstimetorespondtothefuelflowchange.EmergencyProceduresSpecifictoTurboOperationsUnexplainedLossofManifoldPressure Cause: Aleakorrupturesomewhereintheinductionsystem.Theenginewilloperateasanormallyaspiratedengine.Problemposeslittlethreattothesystem.Asdescentfromhighaltitudemaybenecessary.Or; Aleakintheexhaustsystem.Asignificantthreatandmayleadtoenginefire. Itisverydifficulttodistinguishbetweenthepossiblecausesoftheproblem.UnexplainedLossofManifoldPressure Anunexpectedlossofmanifoldpressureshouldbetreatedasanemergency. Powerminimumrequired Bealertforindicationsofanenginefire.Atthefirstsignoffire,shutfuelselectoroffandrefertoinflightfirechecklist. Declareemergency Landassoonaspossible PostMaintenanceConsideration Toensureproperconnectionsofthemanycomponents,intakesandducting,etc,aflighttohighaltitude(17,500-FL250)shouldbeaccomplishedtoensureproperturbooperation. Considercompletingthisflightassoonaspossibleincaseadditionalmaintenanceisrequiredbyyourservicecenter. EngineFailure Onecauseofenginefailuremaybefromreducingthepowertoidlewiththemixturesetnearoratfullrich.Altitudeandfuelpumpoperationwillaffectthefailureconditions.Note:Thecauseoftheenginefailureisanexcessivelyrichmixtureoffuelandair,essentiallyfloodingtheengine.Note:Ifthisisnotcauseofthefailurerefertotheenginefailureinflightchecklistprocedure. Firstreactiontofailure Increasethrottlecontrol Ifthatdoesnotwork Auxiliaryfuelpumpoff Throttle½inchopen Mixturecontrolleanuntilenginestarts Throttle,mixtureandfuelpumpresetfornormaloperation. Richenthemixtureslowlyafterenginestartthenincreasethethrottle.ScenarioShortlyafterlevelingoutat22,000yousetthecruisepower,leanthemixtureandturnyourboostpumpoffandyourenginefails. Whatdoyoudo? Whydidtheenginefail? Seespeakernotesforanswer.Theboostpumpshouldbeleftonfor30minutesintocruiseflighttopreventvaporlockintheenginedrivenfuelpump.Waiting30minutesbeforeturningtheboostpumpoffprovidesampletimeforthefueltocoolandpreventvaporlock.Thewastegateisopen.TheAbsolutePressureControllerwillpositionthewastegatetomaintain29.6inchesofmercuryintheupperdeck,measuredaftertheintercoolers.Theambientpressureatsealevelistypicallyclosetoorabove29.6inchesofmercury.Sincethepressureintheupperdeckisthesameasambientpressureandabove29.6,boostfromtheturbo/compressorisnotnecessary.Wastegateisopen.Boostfromtheturbo/compressorisnotnecessaryatsealevelbecausethepressureintheupperdeckisatorabove29.6.Theturbo/compressorwillboostthepressureintheupperdecktocompensateforthedecreaseinpressureathigheraltitudes.Fuelflowwillbeconstantregardlessofaltitudetomatchtheconstantmanifoldpressuregoingintotheengine.Astheaircraftclimbsthroughaltitudetheambientpressuredecreases.Theabsolutepressurecontrollersensesthedecreaseinpressureintheupperdeckandautomaticallyregulatesoilpressuretoclosethewastegatetoincreasetheamountofexhaustgoingthroughtheturbo.Theturbospinsfasterasaresultoftheincreaseinexhaust,whichspinsthecompressorfastertocompensateforthedecreaseinpressure.Theentireprocesshappensautomaticallyinacontinuouscycle.Thealtitudewherethewastegateiscompletelyclosedisreferredtoasthecriticalaltitude.Meaningtheturboisworkingashardasitcantocompensateforthedecreaseinatmosphericpressure.ThemaximumcertifiedaltitudeoftheturbochargedSR22is25,000.TheturbosystemiscapableofmaintainingsealevelratedpressureuptoandpossiblyaboveFL250.Sincethemaximumaltitudetheturboaircraftcanflyatisrestrictedbycertification,notaircraftperformance,wedonotknowwherethecriticalaltitudeis.Shortanswer-thewastegateisnotfullyclosedatFL250False,CHT’scoolapproximately15°F/.5gphwhenCHT’sarecloseto380°F3optionsareavailabletokeepCHTsbelow380°Fduringaleanofpeakclimb.Increaseairspeed,whichwillincreasetheamountofairflowaroundthecylindersandsacrificeclimbperformanceDecreasefuelflow.DecreasingfuelflowwillhaveacoolingaffectontheCHTswhenoperatingLOP.DecreasingfuelflowwillalsosacrificepowerandclimbperformanceSwitchtoaROPclimbAreductioninfuelflowwhenoperatingLOPwillhaveacoolingaffectontheCHTs.Tryleaningfuelflowapproximately.3GPH.GiveCHTstimetorespondtothefuelflowchange.Theboostpumpshouldbeleftonfor30minutesintocruiseflighttopreventvaporlockintheenginedrivenfuelpump.Waiting30minutesbeforeturningtheboostpumpoffprovidesampletimeforthefueltocoolandpreventvaporlock.