3E FIL - COnnecting REpositories

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AERONAUTICS AND SPACE ADMINISTRATIONNASa: Grcnt N G . oOI TIO LThis represents t; e Final Report for that portion of the "line r"combustioninst bility studies sponsored by 't SAunder BuWepsContract NOw 51-06:36-d.NONLINEARASPECTSpFC ,{;I JSI'IONIHSTABI .ITY ,IN LIOUIDPROPE,LLANT ROCKET MOTORSForSecond YearlyProgressReportthe PeriodI June 1961 to 31 lation,publication,or in part by or for the United StatesPrepared555buse and disposalIn wholeGovernmentis permitted.by:D.T. Hattie,W. C.W. st-ln-ResearchSirignanoAsst-in-Researchby:f.I June 1962Guggenhei m Laboratori es for the AerospacePRINCETON UNIVERSITYPrlncoton,New JerseyProp ul s I on S i ences

oTABLE OF CONTENTSPageIoII.III.APPENDIXTITLE PAGEITABLE2OF pproximationin Instabilityto the VelocityCalculationsof CharacteristicNozzleC.BasicD.NonlinearE.Some Effectsof InjectionDropletand VaporizationRate IVariationonThe Significanceof the Quasi-Steady-StateAssumptionin ransverseA-IE-IF-I

se ndA,,en,ionisPreviouslyinear"combus, ionins,a-I and 2).SponsorshipofNASA inves,mo,ors.and "nonlmore general,heWavesNsG 99-60.in morereleasea,de,all,,hisa,line.Thein a Cylindricalinforma,iontoin Appendix,heC.in some ector3),which2 furnishess,ud i es.is,hecoveredcombus,ionA number ofin Appendiceson onl I near,hebe foundThe history,heisrocke,isareabo,hnonlinearresearchand how i,willareofinin ,he9).repot,as a wholeInrepor,sA summary of,echnicaleffec,sby separa,eExperimen,al(Ref.s,udies,"11near"repot,I i,yfur,herofone specificprogressins,abieffec,sical-experimen,alTo cover,l,leandsubjec,scoveredcon, motorsIncludedckground,heofrela,edB,E and F.D,problemofin Ref.combus, ionwere coveredin reprin,ma,erialresearcho,heris coveredmodestoo,orinstabilityA,generalby ,heformcombus, ionI.insl-abilin an ARSwi,hand history,hisfori,y

velocityInJectioneffectselementspresentwereusedin spinningin antangentialmode osc I I latlons.Using! x 12,6 x 2,tangential2 x 6 end 4 x 3,mode was alteredaffectedout),wherefirstand secondconstantconsistencyoftherelativeSimi lap evidencethefuel-on-oxidizeri hodsnozzletests,ratioofratiospinningtangentiallo another.Alsoin placethetangentialcastingdistributionin the(priortoburn-mode oscillationstherebypulseforwerewavedoubtfailedon theacrossl ractioneachl sting,thespraywhereI 0 same enaturallymotorlongitudinallag andeffects,was notarrangementondeterminedSpecificverselyspinwas finallysectortestedsensitiveclosedue alwas providedVariable-angleoftheofmixturedoubletofone combinationstandingmixturein iorHowever e theremainfan.considerablywas stabilityobserved.toly orientedsectorresultedwithincrementsa attainedin valuesalcohol-oxygenwas thealonesystemsexpectedresult,differenceson thein 6designedparametersImpingingradiallytocompereusing t tinorientedlongitudinallysame distributedpairson theand transinJector560 motor

iawith each pair coveringanglelimit couJd be e -on-oxidizersubjectedtopulsedlimitstestingThe shiftincreasedwithwas reversedtheConcurrentpulsecenterat anglesin /Ddistributedregimeslengthin thealcohol-oxygenmade todeterminelongAlthoughstabilityal I ionsexlstofof osci Ilation.theI itybecausethesensitivein determiningdistributionsA reproduciblefoundpressureorientedfoundwas good.velocitytheInvolvedtowithtwo experimentalusingt ngentlallymotorwas foundmodestestingtestsOnly the lowerdistributionssectorofand transverseface).at the chambervelocityby theapplicabilitymulti-orifice(L/Daxialgood agreementAdditionalholebehaviorvariable-lengthwas used)pparametersuitableinjectoron the transversein the gas dynamicIBO .tudinalthean equal area ofitself.suppl leddataTheseon:theupperdoubletpulselimitwithin izerstrength.shiftdatapulsed limitsconductedratiolimitx 12) t whenpulseHoweverwwasitwasorienl tion).when thepulseorien-became erratic.testingwas a studyin an opticalshock wave pathacrossrockettheofthemotor,chamber,the

,ofpowder chargesinitialamplitudepulsestothemodes in gentialteststhecouldnarrowI lm itsentirerangetendedtoeffectiveAs theoperatingpulsetoinducinglimitssome ofthethefrom of combustionthewerein thesewas usedofthe0 topulsein the l'lspacinginitialF lsetaperecordstandpulserangeforwithForwas employedtheO. I// fansprayspacingfans,mode ataverycertainbein ts.tesl ,directionwithofreproduced.in a number ofinitialThe oxidizer-to-fueleffectiveinjectorpresencewhen a baffleIoweP strengthprogressed,radialsp inn i ng mode reg line overratiotheiketheQl#andO.2 hatalwaysofmode.a narrowassocia dextendtheeffectproduceI ike-on-Iwas notratesabilitytotodecaydiaphragms,rate,onlyused andusingmixtureonsho :lthisandtangentialsensitiveInstabilityshown toindicateinimportantdataofHowever,wereofevenwas normallyregionand decayspinningoperationmode andbe eliminated.pu I sedthebe highlymotorno baffleand burstwas continuedshown toNormalamplitudesystem and abilitytoPulsed I imitstestingspudsinitialtheWhen thefinaliedlcatingtheO.2 aspacingpeak-to-peakwas shown totheatpressureoppositebe theorieniationwave itudemostPatioabovethereverseand high75 psi)t

.high amplitudewaves were producedin thefuel-to-oxidizerMuch of the pulsed limits data can only be consideredtimewith many aspectsBasicthe effectcarriedstudiesof spinningoutconcentratescombustionwayon thetangentialTheoreticalbeing treatedto datebasicdropletworkprinciplesstudysize onis alsotheoreticallyand an extensionandfan are beingAnotherand experimentalto some of the underlyingtheory as conceivedof vaporizationwaves on the dropletand experimentally.Other areasat thisinvestigated.influence of the instantaneousinstability.approachpreliminaryon the spacial distributiontheoreticallyin this area.rigorousstill to bedirection.under-involve ain theinstabilityof these conceptsto thenon IInear case.111.DI USSlONA.InjectionOrientationIn coveringproblemof combustionthe progressinstabilityof the research,in liquid rocketfirst the generalmotorswill bediscussed.In the previousinstabilitywhichspontaneously4,5), the questionimportance.AlthoughcomplexvelocityThisof velocitysubjectlongitudinalthe ssurecombustionbuilds up from a smallsensitivitywas coveredmodes ofmust alsoon "linear"was shownin detailinstabilitybe considered.disturbancecan be explainedis stillShifts(i.e.,Ref.I,to be of considerablein a technicalalone, the transversesensitivityinstabilitymodesreportin terms ofpresentimportant,(Ref. 4).a morebut nowin the stabilityregimes

Bewere caused e motorby the velocityeffectspresent(extend ing d iametr ica I Iy acrosseffects.With the bafflethe spinningtransfermodewas changedstandpoint)necessaryfortransientsin place,standingstabilizationandplacedthe injector) suppressedeitherinstabilitydisappearedormode.were onlyOftensuch bafflesspinningwhenthemode duringbaffleburnedtheinthese(from a heatthelater,Bafflesto the far less dangerousofseconds(Ref. 4).startingaway,themotorrema i ned stab I e.Lookingone nchinjectionethylrefersithetotheorythenumber ofinin thethespudsgroup).perx 12) toppositegroups,When allspinningmode and one odd combinationZn allorientedspuds,degreeofisthecombustionin combustion(Ref.4).as tocancel(thetheAmong thefirstthenumbersecondreferstospuds areorientedin thenaturallyfavored.Other12 x I ng(2 x 5 2 x !).thesewherethemodethea lesser4 x 3 andwhileforarrangementsofdirection2 x 6 arrangementsincludemode toorientationso arrangedshouldfuel-on-oxidizerand a esignedwith(Ref.also12-spudan enhancementsome are6 x 2,thespudsoxygen)some ual(Iinjectionthediameternumber ofsame directionofone directionin Figuree.g.,from a cohol,velocityorientationsspinningthestableThe forimpingements,processthethata means e le

.andthesprayfansthereforefallFirstdiscussingin Figure2 thatrocketchamberwas operateddenotedas wholechambertests.secondsduration.is jection6.liquidnottheThe reasontomoredisplacedimprovestheHow wellthislike-on-likeinjectortesting.When a diamel aichambercombinationtheI.ofspina doubletcombustionin esultingworksoutwas a cryogenicethyltwothata mixtureenhancementofconstant.sidewas foundignitionThe earliestusingwas er.perimeter,thecompared.solidhenceA laterrichtheratiocombustion.in Ref.chamberfan ofby themixture-andfullforfuelbehaviortransducerbe from thesprayvaporizesis more readilytogas anditfashionthreewholedirectionaretwo andusinghydrogenbe detected.thetheconditionsrun on theon thetowardoxidizeroxygenmovementpressurecouldfanFei ler,Ref.wereI x 12 InJector,betweenbe a problemtestswas expectedacrossfromofa 90 intervalsprayoftheconventionalweretransienttoa singledistributionbeinga mixtureexpectationsThe directionofin theTestsreproduciblewavesresultswas accompl lshedhad provedused onlytestradii.a number of operatingIgnitionTwo seriesseriestheon injectoralcoholsuchandhencedisturbances.and enhanceswi I i be shown laterasThisthefromin theI x 12 Injector-mode was eliminated.The stabilitylimit

I0.was shifted1.2t-from1.3.forI sacthefortests,the2).spinningmode (wholemode bafflecaseThe placementofis shown in Figurealuminumhad burnedthestandingin Figureorientationend of1.6away.baffleThisprovided3.chamber(showntheas "withbaffle,was recordedalong1Tansducerpositionbaffle"of allcontactIndicationwithtotypicalAn electricala clearcase)ofon onewhen thetransducerthedatabaffleon theFM tape.Usingspinningtheand aracteristicspinningwave amberand thestablemore thanruns.theAlsoonce as mixturearecase.betweenlimittofoundbe notedratiothat asthatAdditionallimitafterisa proofthata eased.ThisofferedtestedInStance. depbafflethatcasesonlywerewiththeratiowas thetestsbeD).2 Indicatesthisthespinningmodes canAppendixtotoThe charac-tTansverseZn discussingthe4b.transverse(seeThetransducersand eawayp Figurewe HigherThe buildupIs shown in FiguresuggestionbafflepressureIs illustrated.detonationthemanner.4aIn some cases.same twowaves ssociated2 x 6 and 4 X 3),suchchambertheshape5t bothFigurein thispresentby thein l(6 x 2,withbafflepeakedmodes pointAftertangential) aveindicatedbe readilymode datais determinedand thehighermodes couldmodes edfurther

II.proofthat thesespuds wereIn testingspin directionasin theoperationclosethe 6 x 2 and 2 x 6 orientations,was expected.I x 12 caseboth casesnot behaving as the doubletwithno substantialas comparedTeststhe resultschangesto theto the 1.6 mixturewere performedshownratio point.in the same mannerwhich extendedThls was not presenti.e., stabilityWith the bafflefirst tangentialvariationbetweenstandingin behaviordecreasetheI x 12 showedangreater(see Figuretendencydata withtowardThe maximummixtureinstabilitywas

affected was stability behavior with the baffle in place (prior to burn-out), where first and second standing tangential mode oscillations were observed. However e the direction of spin of the tangential wave failed to remain constant with mixture ratio thereby casting doubt on the consistency of the relative mixture ratio distribution across each spray fan. Simi lap evidence was provided in .