—

.

,.

., .-

/

TECHNICALNOTES,. %NITIONALADVISORYCOMMITTEEF@ AERONAUTICS

-—-.

No.344-

PEIWORM.MCEOFA HIGH-SPEED

USINGMULTIPLEORIFICE

—.

,

.

COMPRESSION-IGNITIONEiGIfi.

FUELINJECTIONNOZZLES

-“- ,-.

m,x CCNFW---

WashingtO?lJune,1930

.

* --..-”...--.r...ms.

-j..

..”.-.—---: .--. . :—::’. .:.. .>. .:

,..,~-

,------. .. -!

r

. . ;---.z-. . . .- :.-:

i

,-.

.-.

4

:-!’~’~’~w~!!‘-=:”~““““ -, ~:—.—.

~:”.- =:--=: --:- ., .NATIONALADVISORYCOMMITTEEFORAERONAUTICS.

TECHNICALNOTENO.344.-.

PERFORMANCEOF A HIGH-SPEEDCOMPRESSION-IGNITIONENGINE

USINGMULTIPLEORIFICEFUELINJECTIONNOZZLES.

By J.A.SpanogleandH.H..Foster.

Summaryd

ThisreportpresentstestZesultsobtainedattheLangley

MemorialAeronauticalLaboratoryoftheNationalAdvisoryCom-

mitteeforAeronauticsduringw investigationtodeterminethe● ✌ relativeperformanceofa single-cylinder,high-speed,com-

pression-ignitionenginewhenusingfuelinjectionvalvenoz-S

.-.—-zleswithdifferentnumbers,sizes,anddetectionsofrotid

orifices.A-spring-loaded,automaticinjectionvalvewasused,● .

centrallylocatedatthetopofa verticaldisk-typecombus-

tionchamberformedbetweenhorizontallyopposedinletandex-

haustvalvesof a 5-inchby 7-inchengine.

A seriesoffuelinjectionvalvenozzleswithdifferent

arrangementsofroundorificesweretested,startingwithori-

ficessosmallthati&pingementon thecombustionchamberwalls

wasimpossible&d increasingbeyondthestartof impingement.

Fromthesedatatwomainjetsof0.018-inchdiameterwerede- Btideduponandtheotherjetsvariedinnumber,size,anddirec- ition. A nozzlewastestedwiththeareaoftheorificespropor-

tiOIKd.to theuolumeof airtobe servedby thejets using the#

●

.F.

N.A.C.A.TechnicalNoteNo.344 2

two0.018-inchorificesasa basis.

A tabl?eandcurvessxepresentedshowingtheperformance

oftheenginewithdifferentnozzles.Indicatorcardsandspray

photographsareincluded.Thetestresultsarediscussed,and

someprobablereasonsgivenforthevariationinperformance

withdifferentnozzlesona basisof spraydistribution.Con-

clusionsaredrawnastothepossibleapplicationofthesere-

sultstothedesignoffuelinjectionvalvenozzlesforuse

witha combustionchamberhavinga lowrateof airflow.

Introduction.

Theinformationavailableontheperformancechscacteris-

ticsofhigh-speed,compression-ignitionengineshasusually,been

publishedasresultsoftestsofpaxticulaxengines,andthese-

resultshavebeenjudgedentirelyona basisofbrakehorse-

powerandspecificfuelconsumption.Mqchmoredetailedinfor-

mationisnecessaxyfora foundationuponwhichtobasefur-

therdevelopmentsothattheinherentadvantagesofthistype

of enginemaybe generallyusedinaerialtransportation.

Thefundamentalproblemofthecompression-ignitionengine

isthebringingofallthefuelintocontactwithsufficient

airforitscombustion.Theparticularproblemofthelight-

weight,airlessinjectionengineathighspeedsistoob~ain,

inthesnorttimeavailable,a completemixingandburningof a

fuelchaxgelargeenoughtounitewithalltheinductedair.

s

. .

N.A.C.A.TechnicalNoteNo.344 3

Thetwogeneralmeansof effectingthismixturearethemo-

tionofthefuelandthemotion oftheair,md bothme ef-

fectivetoa certainextentin everycombustionchamber.The

degreeofutilizationofthesemotionsv~ies fromthecombus-

tionchamberdependingslmostentirelyon air flowtothatwhich

hassucha lowrateof airflowthatthemotionofthefuelis

butslightlydifferentfromthatinquiescentairOZthesame

density.

Theuseof airflowusuallyentailsa lossinmechanical

efficiencyaswellasanaddition~heat10SStothecoolant

andatthepresenttimenotenoughisknownaboutpersistent

airflowduringinjectiontoutilizethismeansto itsbestad-

vantage.Sincetheinducedairflowchangesitsvelocitywith

enginespeed,itcanbeutilizedoveronlya limitedrangeof

speeds.

Therefore,itseemeddesirabletc investigatethepossibil-

ityof obtainingtherequisitemixtureof fuelandairby in-

jectingthefuelthro~ha combinationofroundorificesina

nozzle,sothatitwouldbeproperlydistributedthroughoutthe

airina combustionchamber.

T

It isimpossibleto eliminateairPflowentirely,butinthecombustionchamberusedinthisinvesti-.

gatiomtherateappearstobe solowthatthereisno evidence I,.of itsinfluencingthedistributionof thefuel.

BothRicardo(Reference1) andHesselamn(Reference2)have

usedmultipleorifice.nozzles&d havepublishedresultso~-

.——.—

i

6.

N.A.C.A.TechnicalNoteNo.344.,.. . ..... . . . ........

tainedwithdifferentcombustion

reportsexcellentperformance-in. .

4

chambers.Taylor(Reference3)

hisworkwithmultipleorifice

nozzlesattheRoyalAircraft,Establishment.TheNationalAd’vi-

SoryCommitteeforAeronauticshaspublisheda reportbyG~di.nez

(Reference4) onanattempttomakethecompressionspacecon-

formsomewhattotheshapeofthespray.

Thispresentreportincludesdatafromtestsmadewhileat-

tackingtheproblemofdistributionintwodifferentways. ThefirstWasthecommonlyusedmethodof conductinga seriesof

engineperformancetests~d systematic~lyvaryingthenumber,

direction,andsizeoftheorificesuntilthetestresultsin-

dicatedanopti~ valuein snyseriesof changes.Thesecond

methodconsistedinmathematicallyproportioningthedischexge.of eachorificeto thevolumeof airtobe servedby thespray

fromthisorifice.Asa matterofconvenienceandtohavea

basisofcompa.risom,resultsfrom

a startingpointforthe’second.

thefirstmethodwereusedas

Neithermethodaloneisen-

tirelysatisfactory,asyet,fora basisofnozzledesigrsand

theworkalongthislineisby nomeanscomplete.However,theresultsattainedarebeingpublishedatthistimeto showthe

possibilitiesof improvingengineperformancethroughthede-

signoffuelinjectionvalvenozzles.

.

●

N.A.’C.A.TechnicalNote‘No.-344 5

.

.

ApparatusandMethods,.1 Theengineperformancetestsinthisreportweremadeon

anN.A.C.A.Universaltestengine(Reference-5)witha special

head(Fig.1),inwhichthecombustionchamberwasformedbe-

tweentheheadsofhorizontallyopposedintakeandexhaust

valves.Thecylinderhead,fuelinjectionapparatus,andpis.

“tonweredesignedforresearchpurposesby thestaffofthe

NationalAdvisoryCommitteeforAeronautics.Theshapeofthe

combustionchamberandthelocationsoftheinjectionvalveand

maximumcylinderpressureindicatorareshowninFigure8. The

clearancebetweenthepistopcrownandcylinderheadwasbetween

0,030inchand0.040inchattopcenter.Figure3 showsa lon-

gitudinalsectionofthefuelinjectionvalve,andFigure4

showsanenlargedsectionof thefuelinjectionvalve.nozzle.

Thefuelusedwasa goodgradeofDieselengineoilhaving

a specificgravityof0.84~anda Sayboltviscosityof41 sec-

ondsat80°F. Thisoilwasdeliveredto a cam-actuatedinjec- \

tionpumpby a primarygearpumpata pressureofabout135

poundspersquareinch.Theinjectionpumpwasconnectedtothe

‘ injectionvalveby a seamlesssteeltube1/8inchinsidediam-

eter36incheslong. A valveopeningpressureof 3000pounds

persquareinchwasusedthroughoutthetests.Thepumpcamwas

shapedsothatthevelocityof t,heplungerincreasedduringits

stroke,andby meansofanadjustablecamblockcontrolofthe

by-passvalve,. injectioncouldbe timedto occur at various p6r-

.-,

N.A.C.A.Technical.NoteNo.344 6.,,,., . .. . .,.,...

tionsofthepure@stroke,thustakingadvantageofthevarying

-velocityof.

placement.

variedfron

drtvenfrom

theplungerto obtaindifferentratesoffueldis-

Theinjectionperiodindicatedby theoscilloscope

3?to 55crankdegrees(Reference6). Thecamwas

thecrankshaftthroughanadjustable2 : 1 r=~ti~-..., -

tionge~ whichalldwedtheangularrelationbe~we==thecam ‘

andthecrankshafttobe changed,

A 50-75horsepowerelectricdynspometerwasusedto absorb

theenginepowerandtomotortheengineforstartingandfoz.- thefriotionrunsi~ediatelyafterpowerruns. Theindicated.1horsepowerwastakenasthesumofthebrakeandthefriction

horsepowers..

The’engi~e.

andstopwatch,

. consulnptionWas

““”poundoffuel.’

speedwasdeterm~nedby”a revolutioncounter

bothofwhichmereelectricallyoperated.Fuel.-’obtainedby timingthedisplacementof0.5

Airconsumptionwasdeterminedby-anelectric-

- allYoperatedstopwatchwhichtimedthe-displacementof80..“cubicfeetof airfroma gasometer.

tExceptforonetestat speedsfrom400to2000r.p.m.,all

. testswereconductedat

,pressionratiowas13.,6

..

/’

. r

,

werem~intainedat170°

enginespeedsof1500r.p.m.Thecom-

to1. Waterandoiltemperatures(out)

and140°F.,respectively.Theinletair

temperaturewasheldconstantat95°F.duringthetestsoTest

resultsaspresentedarecorrectedto dry air and to a b=o-

metricpressureof29.92inchesHg.

.

●

. N.A.0,.A.TechnicalNoteNo.344 ~,.. ,..- .’.

Compressionpressuresandmaximumcylinderpressureswere

indicatedby & calibratedBourdonspringgaugeconnectedto an

N.A.C.A.disk-typeindicatorvalvewhichwasoperatedby the

pressureofthegasesinthecombustionchamber(Reference7).

Thisapparatuscouldnotbe dependedupontofollowthehigher

ratesofpressurerise,sotheindicatedmaximumcylinderpres-

surescouldnotbeusedasa standardfor.settingtheinjection

advance.Instead,thepumpma~adjustedtogivethedesired ,_fuelquantityandrateof injection,andthenthetimingwas

advanceduntila faintknockwasheard.

Fullloadfuelquantity,0.000345poundpercycleasshown

on theperformancecurves,isthatquantityoffuelwhichwill

be completelyburned,assumingperfectcombustion,withthe.

amountofairinductedperstrokeat87.5percentvolumetric\ efficiency.Testsmadejustbeforepublicationindicatethat

thisvaluemaybetoohighforfullloadoperationasshownby

thecurveinFigure5. However,no changeshavebeenmadein

theperformancedatabecausetheyareusedonlycomparatively

andmy alterationonthisbasiswouldbe favorableto theengine.

Indicatorcar& weretakenwiththeDebbie-McInneselectric

indicatorinthecourseofitsremodelingattheLs.ngleyUemo-

rialAeronauticalLaboratory(Reference-8). Performanceisdis-

cussedontheindicatedbasis,becauseof thelowmechanical

efficiencyofthesingle-cylindertestengine. .

.

.

.

.

,

N.A.C.A.TechnicslNoteNo.344 8

PhotographsofthefuelsprayeweretakenwiththeN.A.C.A.

SprayPhotographyEquipment(Reference9). A fullscalemodel

followingtheoutlineofthedisk-shaped-combustionchamberwas

placedinthesprayphotographypressurechamber(Fig.6),so

thata picturecouldbeobtainedofthespraydistributi&in

thecombustionchamberforeachnozzle.Theedgesofthecom-bustionchambershapewereslightlyobscuredinthephotographs

by thepressure-chmbercoverplate.Theinjectionpressuxes

wereof thesameorderasthoseusedintheenginetestsat.fullloads Thespraychamberairdensitycorrespondedtothat

in a combustionchamberata compressionratioof13.6: 1:

Theorificesweremeasuredeitheron a dividingengineor

withpluggauges.Thelengthof theorificewasmadetwicethe

diameterby counterboringwhennecessary.

TestResultsandDiscussion

Thetestresultsarepresentedintheformof curvesanda

chart(Fig.11)whichliststhenozzlesandgivesdimensionsof

orificesandtfieperformanceobtained.Theresultspresented

maybe consideredaverageandarereadilyreproducible.

Thefirstexperiment~nozzleswerebuiltwiththeideaof .

preventinganyimpingementon eitherthepistonorthecombus-

tionchamberwalls.Figure~ givestheengineperformancewith

someofthesenozzles.Thelimitedperform~ceofnozzlesNos.

3,4, and7 wasduetotheinabilityto injectmorefuelthrough

.

.

.

.N.A.C.A.TechnicalNoteNo,.344 9

.

.

thesenozzlesevenwithexcessivelyhighinjectionpressures,.becauseofinsufficientflowareathroughtheorifices.Figures

7 and8 showtheresultswhen’usinghighandlowratesofinjec-

tion,respectively.Itmaybe seenthattheperform~cecoversa

a greaterrangeoffuelquantitywhenthelowrateof,injection

Isused. ItshouldbenotedthatonlywithnozzleNo.9 ofthis

grouphavinganorificeareaof0.00069squareinchcouldfull

loadfuelbeobtained.

ThedesignofnozzleNo.9, thefirstoftheseven-orifice

typehavingalternatelargeandsmallorifices,wasbasedonthe

assumptionthatthespraysfromthesmallorificeswi~htheir

shorterpenetrationdistributefueltothatpmt of thecombus=

tionchambernearertheinjectionnozzle.Thevalueofthesefillerspraysasanaidto distributionmayberealizedwhenit

isconsideredthatthesprayasshownin a photographdoesnot

containa uniformlydispersedquantityof fuel,butthatitoon-

tainsa relativelydensecore,mostofwhicheventuallytravels

almosttothespraytip.

TheengineperformanceobtainedusingNo.9 nozzlewaxranted

thecontinuationoftests,anda definiteprogramwasstarted

to determinetheeffecton engineperformanceofvarying,first,

thetwomainorificeswhichdeliverfueloil to that portion of

theairchargeintherectm~~ orificedirectlyabovethe

pistoncrownand,second,theotherorificeswhichdeliverfuel

to theairintheupperpartof thecombustionchmber. Figure.

.1

.

N.A.C.A.TechnicslNoteNo,344 10

9 showstheengineperformanceresultsatfullloadfora range

of sizesforthetwomainorificesB fromO.010-inchto0.021-

inchdiameter(Fig.4). The”partoftheinjectionpumpcsmgiv-

ingthehighestrateofinjectionWasusedinobtainingthis,.

performance.Itmaybe seenfromthecurvesthatthe0.018-inch

orificesmaybe consideredtheoptimumdiameterforthetwo

maimorifices.Theresultsshowthatthei.m.e.p.increased

from101to125poundspersquareinch,withan increaseinori-

ficediemeterfrom0.010inchto0.018inch.Thecorresponding

fuelconsumptiondec~easedfrom0.586to0.458poundperi.hp

perhour. A furtherincreaseinmaimorificediameterfrom .

0.018inchto 0.021inchresultedina slightdecreaseinpower~

Thisindicatesthatorificeslargerthan0.018inchsupplied

morefuelthancouldbeburnedefficientlyby theairinthat

partofthecombustionchamberservedby thesejets.

Inspectionof thecarbonformationonthecrownofthe,pis-

tonshowedthatallthespraysfromorificesof0.012inch02

largeractuallyimpingeduponthepistoncr,own.Sincethespe-

cificfuelconsumptiondecreasedastheseB orificeswereen-

largedto0.018inch,itmaybe saidthatimpingementof a spray

doesnotnecessarilymeanthatit isnotavailableforcombus-

tionafterimpingement,orthatoilparticlesmakingcontactwith

a wallwillclingto itandnotignite.1+istruethatthese

sprayswerestrikinghightemeratuxew@ls, butlateremeri-

mentsshowedthatthessmewastrueof sprays,i~pingingupon.

.

.

.

.

N.A.C.A.TechnicalNoteNo.344

coolersectionsofthecombustion

inchozificesdischargeda larger

11

chamberwalls.The0.018-

quantityoffuelthanthe

0,012-inchorifices,md thisextraquantityoffuelseemedto

be necess~yfortheutilizationoftheairavailableforthese

sprays.

Figure10 showstheeffectonengineperformanceofchang-

ingonlythetwooutsideorificesD (Fig.4),whichdeliver

fueltotheairch~geintheuppermostpartofthecombustion

chaber,from0.006inchto0.012inchfornozzleshavingtWo

0.018-inchdiameteranainorifices.Fromtheresults,0.010

inchappe~s

At-fullload

squareinch,

tobe theoptimumdiameterfortheoutsideorifioes.

thei.m.e.p,increasedfrom114to126poundsper

foranincreaseinorificediameterfrom0.006inch

to 0.010inch.Thecorrespondingfuelconsumptiondecreased

from0.50to0.4~5poundperi.hpperhour. AVincreaseindi-

ameterofthesetwoorificesfromO.O1Oinchto’O.012inchcaused

a slightlysmokierexhaustwithapproximately1 percentincrease

inpoweroutput.ThisindicatedthattheO.010-inohorifioes

suppliedtheproperproportionoffuelfortheairavailablein

thepart ofthecombustionchamberservedby thesejets.

Thechart(Fig.11)showstheeffectonengineperformance

of changingtheorifice~C from0.005inchto0.012inch.This

isshownasthediffe~encebetweennozzlesNOS.l? and18,and

indicatesthatthe G orificesshouldbe consideredasfiller

orificeswhenusedincombination’withthelargerD orifices.

.

.

.

.

.

.

N.A~C.A.Technic&1NoteNo.344 12

Thischangedecreasedthei.rn.e.p.from126to116poundspet

squareinch,andincreasedthefuelconsumptionfrom0.48to

0.52poundperi.hpperhourduetoa lessuniformdistribution

of thefuel.Sprayphotographstakensomemonthsaftertheen-

ginetestsshowedthatthisWasprobablyduetobothspraytips

beingprojectedintothesamespaceby differentpaths.The

photographsshowthattheoilsprayisreflectedfromthewall

of thecombustionchsmber,buttheenginedatado notindicate

thatthesprayisabsorbedby thecarbonon thewall,orthat .

thecomparativelycoolwallcausesanycondensation~f thes~-ray.

Figure12 showsa comparisonofperformancewiththeseries.ofnozzlesdesignedsothattheexeaof theorificewouldbe

proportional.tothevolumeof airitserved.Thebasisofthis

proportionwastakenastherelationbetweentheareaofthetwo

main0.018-inchorificesandtheairincludedintheirspray

angleplustheairintheclearancespaceaboutthepistoncrown.

Thefirstnozzleofthisserieswastestedwithoutthefiller

orificeA. Theadditionof an0.007-inchfillerorificein-

creasedthei.m.e.p.from122to130poundspersquareinch,

anddecreasedthefuelconsumptionfrom0.49to0.46poundper

i,hpperhour. Enlaxgingthisfillerorificeto0.010inch

slightlyincreasedthemeanpressure? .

Thisnozzlewithnineorifices(Fig.13)gavesucha slight

increase thatitwasquestionablewhetherthisincreaseWasI

worththeaddedcomplicationoftwoextraorifices.Inthispa&

N.A.C.A.Technic&l.NoteNo.344 13

.

ticul~nozzletheouterE orificeswerecrowdedintothecoz-

nersothatlessareaWaseqosedtotheimpactoftheoiland,

therefore,therewaslessdisch~gethroughthemthanwouldbe

expected.Thiswassuspectedatthetimeoftheenginetests

andsubsequentlyconfirmedbythesprayphotographs.A very

smallamountof sprayisvisiblefromtheseouterorificesin

photographstakenbothwiththedummycombustionchamberinplace

andwithoutit.

F~omthetestresultsit isapparentthatthesmallfiller

spraywasanimportantfactorinsecuringgoodfueldistribu-

tion.withresultanthigherpowerandbetterfueleconomy.The

fillerspraysuppliedfuelto airinwhichthereseemedtobe

verylittlefuelremainingfromthepassageo~themaimsprays

throughit,althoughthesprayphotographsshow

thisspace.

Figure14 showstypicalengineperformance

somesprayin

curvesfora

constantspeedof1500r.p.m.,a variablefuelquantity,a con-

stantinjectionadvanceangleof45°, ‘“”’””7 ‘“anda~w rat~ofinjec-

tion. Thepointsmarkedwithcircleswereobtaimdby increas-

ingtheinjection,advanceangleinincrementsof2°,andthey

shoWthatthel~ge increaseinm~imumcylinderpressureWas

outofproportiontotheincreaseinme~ effectivepressure

gainedinthisway. A compaXisomofthesecurveswiththoseof

Figure15 fora higherrateof injectionshowsthattheyare

somewhatsimil~,hutthecylinderpressures~e higherforthe

.

.

.

N.A.C,A.TechnicalNoteNo.344 14

lowerrateof imjection.Figuxe16 showsengineperformance

results for a range of injection advance

Figure17 showstheeffectofspeed

formancewithfullloadfuelfrom400to

rateof injection.Fourhundredr.p.m.

angless

on generalengineper-

2000r.p.m.anda low

wasthelowerlimit

.

.

for consistent operation with full loadfuel,slthoughtheengine

wouldidleat135r.p.m.Theconsistentlylowspecificfuel

consumptionfrom800to1800r.p.m.showsthedesirablecharac-

teristicof constantfuelconsumptionovera rangeofspeed.

Thisalsoindicatesuniformcombustionefficiencyand,therefore,

absenceofanyeffectsof airflow.Thisabsenceof effective

airflowagreeswiththeresultsofRothrocklsandBeardsleyls

investigation(Reference10)of theeffectofairflowon sprays

in anapparatussimulating{heconditionsencounteredinthe

passagebetweenthecombustionchamberandthecylinderofthis

engine. #

InFigures14 andl? areshown,forcomparison,brelceper-

formancecurvesfora multicylinderenginewithanassumedeffi-

ciencyof85percent,ascalculatedfromthedatasecuredon

thesingle-cylindertestenginewhoseefficiencyis about??5

percent. ‘

Figures18,19,and20 showpressure-volumecardsplotted

frompressure-timecardstakenwiththemodifiedllFa.rnboro’t

indicator.A completeanalysishasnotbeenmadeof thesecards,

buttheyareincludedtoshowthevariationsinthecyclewith.

._—-

.

.

N.A.C.A.TechnicalNoteNo.344 15

changesintheinjectionadvanceangleandintherateofinjec-

tion. InFigure19 theinjectionadvanceanglehadbeenin-

creased5°overthatinFigure18. Figure20 showsa cardtaken,

witha lowrateofinjectionanda largeinjectionadvanceangle.

Figures21 and22 showpicturesofthespraysfromnozzle

No.9, withinjectionpressuresof4350poundspersquareinch

and3200poundspersquaeinchwhichcorrespondto themsximum.

injectionpressureatfullloadforthehighandlowratesof

injection,respectively.

Figure23 showsa pictureofthespraysfromnozzleNo.12-1

whichhadouterorificesof0.012-inchdiameter.Itmaybe seen

thattheouterspraystnnozzleNo.1~-1struckthesideofthe

chamberandweredeflecteddownwardintootherwiseunreached

air,therebyaidingthefueldistribution.Figure24 shows

spraypicturesfornozzleNo.16-2whichhadouterorificesof

0.008-inchdiameter.

Figure25 showspicturesof spraysfromnozzleNo.12which

hadtwomainorificesofO.O1Oinchas comparedto0.018inch

forallothernozzles.Duetothereducedorificearea,thein-

jectionpressureatthehighrateofinjectionWas6800

persquareinchascompsxedwith4~50poundspersquare

othernozzles.

pounds

inchfor

Figure26 showspicturesof spraysfromthenine-orifice

nozzleNo.G2. Lackof’smorepronouncedoutlineofthesprays

maybe attributedtooverlappingcausedby crowdingofthese

.

.

.

,N.A.C.A.TechnicalNoteNo.344 16

comparativelylargesprays.

Cone lU s i o n s

Theresultsofthisinvestigationshowthatto obtaineffi- -

cientcombustionin a cylinderheadwithlowratesof airflow

duringtheinjectionofthefuel,itisnecess~ytoproportion

anddirectthefuelsprayssothatthefuelisdistributedas

uniformlyas”possiblethroughouttheair.

Theengineperformanceobtainedbyproportioningtheareas

of theorificesto theuolumesof airtobe servedby eachor-

ifice was approximately thesameasthatobtained

allorificesizesanddeterminingfromtheengine

timumcombination.

,

time

ther

Themathematicalmethodisconsiderablyless

by varying

power the op- ,

expensive im

andmaterialthantheexperimentalmethod.However,nei-

is completeinitself,andbothcanbe aidedconsiderably

by thestudyof sprayphotographs.

Theenginetestresultsindicatethatimpingementofthe

f~elsprayon thepistonandchamberwa,llsisnotnecessarily

detrimentalto combustion,butmaybe anaidtodistribution.,

Smallfillerjetsareimportentaidstodistribution.L Fitting

visiblesprayoutlinesto combustionch~bercon!toursdoesnot

insuxe a perfectmixture,becauseofthevarying

fuelirithevisiblespray.

Althoughengineperform~ceistheultimate

densityof the

standardby.

.

N.&C.A.TechnicalN@e No.344

whichthevalueof anyparticular

be determined,theperformanceof

1?

combinationoforifioesmuq~

theengineisnottobe en-

tirelyreliedupon to indicate the worth of any combination for

development purposes. Thesameperformancevsluesmaybe at-

tainedby differentcombinaticms,oneofwhichmaybe theop-

timumof a particularmeansof improvement,whiletheother

mightbemerelyanintermediatepointalo~,alinethatleads

topossibilitiesof evenbetterperformance.

LangleyMemorialAeronauticalLaboratory,.NationalAdvisoryCommitteeforAeronautics,

LangleyField,Vs.,May28,1930.

.

?

.

N.A.(2.A.TechnicslNoteNo.344 18

,. Ref e r enc e s

1.‘Ricaxdo,H:R. :

2. Hesselrnan,K. J.E. :.

#3. Taylor,H. B. ●

●.

,Compression-IgnitionAircraftEngines.AircraftEngineering,Vol.I,No.3,May,1929,pp.82-88.

46

.-

t

5.

.’

6.

.

7.0

8.

9*

10.

HesselrnanHeavyOilHigh-CompressionEngine.N.A.C.A.TechnicalMemoran-dumNo.312,1925.

High-SpeedInternalCombustionEngineResearch.JournaloftheRoyalAero-nauticalSociety,July,1928,pp.555-Cn=

. - –. ., .-tiaramer,A. w. 9●

Ware,Marsden,

Hicks,Chesterand

Moore,Charles

‘Hicks,Chester

●s

w.●

s. ‘

w. :

Collins,Jr.,J.H. :I

Beardsley,E. G. :

Rothrock,A.M.anti ●

●

Beardsley,E. G.

.

A PreliminaryStudyof FuelInjectionandcompressionIgnitionasAppliedto m AircraftEngineCylinder.N.A.C.A.TechnicalReportNo.243,,1926.“DescriptionoftheN.A.C.A.UniversalTestEngineandSomeTestResults.N.A.C.A.Technica3ReportNo.250,192?.TheDeterminationofSevera3SprayCharacteristicsofa High-SeedOil

xEngineInjectionSystemwit anOs-cilloscope.N.A.C.A.TechnicalNoteNo.298,1928.

TheMeasurementofMaximumCylinderPressures.N.A.C.A.TechnicalReportNo.294,1928.

LaboratoryDevelopmentofthe‘lFarn-borol~EngineIndicator.N.A,C.A.TechnicalNote(tobepublishedlater).

TheN.A.C.A.FuelSprayPhotography-ApparatusandTestResultsfromSev-eralResearches.N.A.C.A.TechnicalReportNo.224,192?.

SomeEffectsofAirFlowon thePene-trationandDistributio?x.ofOilSprays.N.A.C.A.TechnicalNoteNo*329,1929.

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DE5CRlf T/ON. OF FUEL VAIL VE NO Z ZL~ A“ND .S OMETLTS T R15.5u!. T.S FOR FULL LOAD FUEL AT 1500 IP. PM.

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N,A.(Y.A.TechnicalNoteNo.344 Fig.15.

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