1、_ -NATIONALADVISORYCOMMITTEEFOR AERONAUTICSTECHNICAL NOTE 2069CYLINDER-HEAD TEMPERATURES AND COOIANT HEAT REJECTIONOF A MULTICYLINDER UQUID-COOLED ENGINEOF 1650-CUBIC -INCH DISPLACEMENTBy John H. Povolny, Louis J. Bogdanand Louis J. ChelkoLewis Flight Propulsion LaboratoryCleveland, OhioWashingtonAp
2、ril 1950 ,-.:. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-THIBF?ARY=M:11111111111111111111111Ollb5278AERONAUTICScxLINmR-HEADTEMPERATURESAND COOIANTHEATlldtemperaturesand thecoolantheatrejectionofisINTRODUCTIONthe coolingcharacteristicsof recipro
3、catingessentialfor thepredictionof enginewProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-2 NACATN 2069performanceat extremeconditionsof operation.Consequently,aresearchprogramwas conductedat theNACAClevelandlaboratoryin1943to investigatethecoolingch
4、aracteristicsof liquid-cooledaircraftengines. The initialphaseof thisresearchprogramconsistedof an investigationconductedon two single-cylinderenginesto providedatafora fundamentalstudyof theheat-transferprocessesinvolved.Thesedata,whichisolatetheeffectsof thevariousengineand coolantvariableson thec
5、ylinder-headtempera-tures,arepresented.inreference1. A semiempiricalmethodbasedon thetheoryof heattransferby nonboilingforcedconvectionandusedfor correlatingthecylinder-temperaturedataof reference1withtheengineand coolantvariablesis presentedinreference2.Concurrentwiththeinvestigationon thesingle-cy
6、linderengines,the coolingcharacteristicsofa multicylinderengineof1710-cubic-inchdisplacementwereinvestigatedoverwiderangesofengineand coolantconditions.Theresultsof thisinvestigationarereportedinreference3,whichpresentsthevariationof boththecylindertemperaturesand coolantheatreectionwith theprimarye
7、ngineand coolantvariables.A correlationof thecylinder-head-temperatureand coolimt-heat-rejectiondataof ref-erence3 withthepertinentengineand coolantvariablesis pre-sentedinreference4. Themethodof correlationisbasedon thetheoryof nonboilingforced-convectionheattransferand is similarto thatdevelopedin
8、reference2.In orderto deterdne if thetrendspresentedin reference3aregenerallyapplicableto liquid-cooledmulticylinderaircraftengines,a similar investigationof thecoolingcharacteristicsofan engineof 1650-ctabic-inchdisplacementwas conductedduring2946and is reportedherein. The cylinder-headtemperatures
9、and.thecoolantheatrejectionweredetezmfnedforpoweroutputsup to2000brakehorsepoweroverwiderangesof enginespeed,manifoldpressure,fuel-airratio,inlet-airtemperature,ignitiontiming,efiaust pressure,andforvariousconditionsof coolantflow,composition,temperature,andpressure.Rumsweremadefor coolantflowsas br
10、as 49gallonsperminutein orderto investigatethecoolingcharacteristicsof thisengineunder boilingcoolantcon-ditions.Thevariationof thecylinder-headtemperaturesandthecoolantheatrejectionwiththeengineand coolantvariablesispresentedanda comparisonismadeof theresultsof thisinves-tigationwiththoseof the inv
11、estigationof theengineof 1710-cubic-inchdisplacement(reference3). Thesecylinder-head-temperatureandcoolant-heat-rejectiondatawerecorrelatedbymeansof theNACAcorrelationmethod,whichis fullyillustratedinreference4, andthefinalresultsof thecorrelationarepresentedto aid intheapplicationof thedata. An exa
12、mpleoftheuseof thecorrelationmethodforthepredictionof cylinder-headtemperaturesandthecoolantheatrejectionis alsoincluded.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-.NACATN 2069.An investigationAPPARATUSEngineswas conductedon two standardproducti
13、on-modelPackardV-1650-7engines,whichshallhereinafterbe designatedenginesA andB. The V-1650-7engineis a 12-cylinder,liquld-cooledenginewitha boreof 5.4inches,a strokeof 6.0inches,anda displacementof 1650cubicinches. The compressionratiois 6.0and theengineisfittedwitha two-stagesuperchargerhavingimpel
14、lerdiametersof 12.0and 10.1inches. The twoimpel-lersaremountedon thesameshaftand canbe operateti,atspeedsof either 5.802 or 7.349 ttiestheenginespeed. A liquid-teaftercooleris interposedbetweenthesuperchargeroutletantitheintakemanifold.Thevalveoverlapextendsovera periodof timeequivalentto 430 rotati
15、onof the cmnlcshat%.The ignitiontimingis controlledby thethrottzepositionand.variesfrom29B.T.C.forfull-closedthrottleto approximately45B.T.C.forfromhalf-to full-openthrottle.Boththeintakeand exhaustsparkplugsarettiedto firesimultaneously.For thevariable-ignition-timingruns,thespark-controllinkagewas
16、 disconnectedfromthethrottleand operated.by an indepetientcontrol.GeneralEngineSetupA photographof oneof theenginesmounteclfor the coolinginvestigationis shownin figure1.Powermeasurement.- The enginesweremountedon a dynamometerstandequippedwitha 3000-horsepower,water-gap,eddy-currentnamometer. The e
17、nginespeedwas electronicallycontrolledandmeasured,by a chronometrictachometer.The torquetransmittedtothedynamometerwasmeasuredwitha Calibratedair-balanceddiaphragm.Combustion-airsystem.- Combustionairwas suppliedto theengineby thelaboratorycentral-supplysystemandwasmeteredwithunadjustableorificeinst
18、alledin thesupplyduct. The tem-peratureof theairwas regulatedbypassing it througheitheraheateror a refrigeratorunitin thesupplyline;theairwascleanedby meansof a filterunitinstalledin thelinedownstreamof theorifice. thermocouplesandpressuretapswereinstalledat theorificesadat the carburetorinlettomeas
19、urethe temper-atureandthepressureof theairat theselocations.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-43imEnasti3ystem. - The engineexhaustgasesmeansofthelaboratorycentralexhaustsystam,NACATN 2069wereremovedbywhichalsoprovidedthedesirede-ust pr
20、essures.Water-jacketed.-e-ust stat-ksthathad stackopeningsequalin areato theetiuat portopeningswereusedfor theinvestigation.The stackswereconnectedto a 10-inch-diameterheaderinwhichwalltapswereinstalledfor thenwasure-mentof theetiust-gasbackpressure.Enne coolantsystem.- A Magammatic sketchof theengi
21、necoolantsystemis showninfigure2. Anauxiliarypump installedin serieswiththeenginepmp permittedthe coolantflowto bevatiedindependentlyof theenginespeed. The coolantflowwasmeasuredwitha venturi. A throttlevalveinstalleddownstreamoftheventuriwas usedto tnoreasetheventuri-throatpressuresuffi-cientlyto p
22、reventcavitationduringoperationat highcoolantflowsand lowcoolantpressures.Centrifugal-typevaporseparatorswereinstalledin theanginecoolant-outletlinesto removeair or anyvaporthatresultedfromboilingof thecoolant.VentlineswererunframboththevaporseparatorsandtheMock outletsto anexpansiontank. Sightglass
23、eswereinstalledinbothsetsof ventMnes to permitvlaualobservationof thecoolantcondition.Acompressed-airandbleed-linecombinationon thecoolantexpansiontankpermittedregulationof thee-ion-tank pressure.The coolanttemperature-controltit consisted of twoaircraft-typecoolersandan air-operated,thermostaticall
24、ycontrolledthree-waymixingvalvelnstalledatthe junctionof a main linefromanda bypassline aroundthecoolers. Waterwasusedto cooltheenginecoolantsolutionsandtheflowwasmeasuredwithcali-bratedrotameters.Thermocouplesandpressuretapswureinstalledat thelocationsindicatedinfigure2.The coolantflowpaththroughth
25、ecylinderbankis schemati-callyshowninfigures3 and4. The coolantis distributedtothe s%barrelsof eachcylinderbankby meansof an externalcoolantbranchtube. Thiscoolantbranchtube,whichis connected to thedischargeof theine coolantpump,has threeoutlets,eachsuppQing coolantto twoadjacentcylinderbarrels. Aft
26、erenteringthebamels, thecoolantflowsarotuileachcylinderbarrelandup intothecyltnderheadsthroughthe 14 connectortubes.The coolantthensses overthecylinderheadsand is dischargedthrougha singleoutletat theforwarded of thecylinderbank.Itmaybe seenfromfigure4 that theflowovereachcylinderheadis equalto thet
27、otalof all theflowsthroughtheconnectortubesupstreamof thecylinderheadin question.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACATN 2069 5For convenientidentification,themanufacturersdesignationof thebanksand.cylindersis usedin thisreport. Thus,w
28、henfacingtherearof theenginetheright-handbankis calledbankAandthe left-handhankis calledbankB. The cylindersof eachbankarenumberedfrom1 to 6 startingat thefrontof the engine.thetetraethyl-leadconcentrationwas increasedto 6 millilitersper gallon. Thelubricatingoilusedthroughoutthe investigationwasNav
29、y1120.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACATN 2069Thermocouplehstallation.Thermocouplesforengine-temperaturemeasurement.- Thecylinder-headthermocoupleinstallationis showninfigure7.Thezznocoupleswereinst=lledon eachcylinderin the clinde
30、rheadbetweentheetiaustvalves,betweentheintakevalves,and in thecenterof thehead. Thethermocoupleholesin thecylinderheadsweredrilledwiththeaidofJigsto insureuniformityand accuracyof location.The cylinder-headthermocoupleswere silver-solderedintobrassplugs,whichwerepeenedintothebottomof thedrilledholes
31、. The leadsinsidetheenginewerepackedinporcelaincementandencasedin stainless-steeltubing. The leadsoutsidetheenginewereinsulatedwithflexibleglasssleevesandprotectedwithignition-typeshieldtng.Thetemperatureswerereadon aself-balancingdirect-readingpotentiometerandrecordedon aself-balancingrecordingpote
32、ntiometer.The inlet-manifoldtemperaturewasmeasuredwitha singleunshieldediron-constantanthermocouplelocatedapproximately10 inchesdownstreamof theaftercooleroutlet.Thermocouplesfor liquid-temperaturemeasurement.- TWO tyyesof thermocouple,iron-constantanand copper-constantan,wereinstalledin theengine-c
33、oolant,aftercooler-coolant,lubricating-oil,and cooling-waterIinqsat thelocationsshownin figures2,5, and 6. Theiron-constantanthermocouplesmre connectedto botha self-balancingdirect-readingpotentiometeranda self-balancingrecordingpotentiometer.The copper-constantanthermocouples,whichwereusedforan acc
34、uratedeterminationof thetemperaturediffer-encesacrosstheengineand coolers,wereconnectedto a portableprecision-typepotentiometerandba.lancewas indicatedona liand (2)fromthemeasuredtemperatureriseandflowof the coolantcoolingwater. Theheatrejectedto theenginecoolantispresentedon thebasisofmethod(2)beca
35、useat lowflowswhenlargeamountsof vaporwereformedmethod(1)wouldnotincludetheheatof vaporization,and at highflowsdifficultywas experiencedinaccuratelymeasuringthesmalltemperatureriseof thecoolantincurredin passingthroughtheengine. ThemaximumdifferencebetweentheheatrejectionsasttetenMnedby eachof thetw
36、omethods,however,wasnotmorethan10percent. The externalheatlossfromthecoolantpipingandexpansiontankwas esttitetito be lessthan2 percentof thecoolantheatreection.The datawerenot correctedfor thisloss.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA
37、TN 2069 9RESULTSANDDISCUSSIONThevariationof the cylinder-headtemperatureand the coolantheatrejectionwiththebasicengineand coolantparameterswas,in somecases,obtainedfor onlya singlesetof operatingcondi-tions. It is believed,however,thatthevariationsshownaregeneralinasmuchas themorecomprehensiveinvest
38、igationof refer-ence3 indicatedthatthetrendsof cylindertememturesor heatrejectionwithprimaryengineand coolantvariableswerethe same- for severaloperatingconditions.Partof thisinvestigationwas conductedwithengineA andpartwithengineB; thereforeall thevariablesconsideredwerenotinvestigatedon a singleeng
39、ine. A comparisonofdatafromeachengineat similaropemting conditionsshowed,however,thatthetrendsandthemaitudes Ofboththe cylinder temperaturesandheatrejectionwerethe s=e forboth engines. .RelationsAmongCylinderTemperaturesTherelationbetweentheaveragetemperaturein the centerofthe cylinderheadand theave
40、ragetemperaturein the cylinderheadbetweentheefiaustvalvesis showninfigure8 forall thedataforbothenginesat thevariousoperatingconditions.A linearrelationexistsbetweenthesetemperaturesandthescatterof thetitsiswithin+350)?. Theaveragetemperaturein the centeroftheheadwasfrom500to 70F lowerthantheaverage
41、temperaturein ttlecylinderheadbetweentheetiaustvalves.Thevariationof theaveragetemperaturein the cylinderheadbetweentheintakevalveswiththeaveragetemperaturein thecylinderheadbetweentheexhaustvalvesispresentedin figure9for engineA at threevaluesof enginerunningtime. A separatestraightlinefitsthedataf
42、or eachrunningtimeandthe slopeof thelinesis the same. The effectof enginerunningtimeonthecylindertempe=turesis subsequentlydiscussedin connectionwithanotherfigure. Themeanscatterof thedatais about+5 Fand theaveragetemperaturein thecylinderheadbetweentheintakevalvesed fromabout45to 70F lowerthanthatb
43、etweentheetiaustvalvesat an enginerunningtimeof 15hours,and about100oto 11OoF lowerat an enginerunningtimeof 95hours.As a resultof the linearrelationexistingbetweenthetem-peraturesin thevariouslocationsin the cylinderheads,theProvided by IHSNot for ResaleNo reproduction or networking permitted witho
44、ut license from IHS-,-,-10variationof onlyoneofvariables is presented.NACATN 2069.themwiththeprimaryengineand coolantTheaveragecylinder-headtemperaturebetweentheefiaustvalveshasbeenchosenfor thispurposebecauseitwas thehighestaveragetemperaturemeasuredand is thereforemostindicativeof criticalcoolingc
45、onditions.Therelationbetweentheaveragetempemtureof the 12 cyl-indersin theheadbetweentheetiaustvalvesand thetemperatureof thehottestcylinder(maximummeasuredfor thesamelocationispresented.infigure10forall thedata. For the conditionsinvestigated,themaximumtemperaturegenerallyoccurredon cyl-inderA6 and
46、 occasionallyon cylindersB6 andA5. A linearvaria-tionisnotedforbothenginesfortheentirerangeof tempe=turesmeasuredandthemeanscatterof thedatais about+15F. Themaximumtemeraturerangedfrom30to 60?3higherthantheaver-agetemperature;thedifferenceincreasedwiththemagnitudeof thetemerature.A linearvariationwa
47、s alsoobtainedbetweenthemaximumandaveragetemperaturesfor theotherthermocouplelocations.Thevariationof theavemge cylinder-headtemperatureswithenginerunningtimeispresentedin figure11. The datapre-sentedwereobtainedat a referenceoperatingconditionfrom timeto timeduringthecourseof the runs on engineA. T
48、he coolantusedforthisreferenceoperatingconditionwas composedof30-percentethyleneglycoland 70-percentwater. Coolantsofothercompositionswereused,however,betweentherunsat thereferenceoperatingcondition.For an increasein enginerunningtimefrom15 to 115hos, boththeaveragetemperaturesin thecylinderheadbetw
49、eentheefiaustvalvesandin thecenterof theheadincreasedabout45F, whereasthetemperaturebetweentheintakevalvesremainedapproximatelyconstant.A closeinspectionof thecoolantpassagesina scrappedcylinderheadrevealedscaledepositsin theexhaustsideand in the-centerof theheadbutnonein theintakeside. The increaseof thetemperaturesin theex
