1、co*NATIONALADVISORYCOMMITTEEFORAERONAUTICSTECHNICALNOTE3170AN EXPERIMENTAL INVESTIGATIONAT LOW SPEEDSOF THEEFFECTS OF LIP SHAPE ONTHE DRAGAND PRESSURERECOVERYOF A NOSEINLET IN ABODYOF REVOLUTIONBy JamesR. BlackabyandEarl C. WatsonAmes AeronauticalLaboratoryMoffett Field, Calif.WashhgtonApril 1954Pro
2、vided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TECHLIBRARYKAFB,NMl!llilllll!llllllnllllNATIONALADVISORYCOMMITTEEFORAERONAUTICS 0ttb5834ANEXPERIMENTALTECHNICALIim 317c)INVESTIGATIONATLOWSPEEDSOFTHEEFFECTSOFLIPSHAPEONTEEDRAGRECOVERYOFA NOSEINLETBODYOFREV
3、OLUTIONByJsmesR.BlackabysadEarlSUMMARYANDPREssmINAc. WatsonWind-tunneltestsofabodyofrevolutionwitha circularnoseinletwereconductedatlowspeedstoascertainsomeoftheeffectsofinletlipbluntnessandprofileondiffuserperformanceandbodydrag.The4testswereconductedatfree-streamMachnumbersupto0.330withinletflowsf
4、romzerothroughchoking.Boththeangleofattackandtheangleofyawofthebodywere throughouttheinvestigationA sharpinletlipprofilewastestedinadditiontofivecircular-arcandtwoellipticalprofiles;thevariousprofileswereccmparedintermsoftheirshapesandcontractionratios,theratiooftheareacircumscribedbytheleadingedgeo
5、ftheinletliptotheminimuminletarea.Aswouldbeexpected,thesharplipprovidedthepoorestpres-surerecoveryformass-flowratiosgreaterthan1.0foralloftheMachnumbersofthetest.Theimprovementovertheinternalflowcharacter-isticsofthediffuserwiththesharplip,causedbya slightbluntnessofthelipoftheinlet,dependedtoonlya
6、smallextentontheshapeofthelipprofile.However,formoderatebluntnesstheeffectoftheshapeoftheprofileassumedimportance,withanepticalprofileprovidingbetterpressurerecoverythana circularprofile.Dragandsurface-pressuremeasurementsshowedthatformass-flowratioslessthan1.0thechangeoftheexternaldragofthebdy with
7、mass-flowratiowascausedalmostentirelybythechangeofthesuctionpressuresinthevicinityoftheinlet.h addition,themagnitudeofthechangewasfoundto.beequal,butofoppositesign,tothechangeofthecalculatedadditivedragfortheinletaslongastheexternalflowwasnotseparatedfromthelip. Pressureandvisualstudiesoftheflowinth
8、einletindicatedthata combinationofobliqueandnormalshocksoccurredfitheinletportionformassflowsnearthatrequiredforchoking.l%essuremeasurements.inthediffuserindicatedthat,withtheinletchoked,theamplitudeofthetotal-pressurefluctuationswasasgreatas15percentof-theProvided by IHSNot for ResaleNo reproductio
9、n or networking permitted without license from IHS-,-,-2 NACATN 31709free-streamtotalpressure.Thefrequencyofthesefluctuationswasoftheorder-of20cyclespersecondorless. .INTRODUCTION - Twofactorstobeconsideredintheselectionofa lipprofileforaninlettosupplyairtoa turbojetenginearethedesignMachnumberandal
10、titudeandoff-designoperation.Urally speaking,thefirstofthesefactorsisofprimaryimportanceandforgoodperformanceashsrplipprofileisrequiredforsupersonicflowanda roundedlippro-fileisrequiredforsubsonicflow.Thesecondfactormayassumeimpor-tancewitha sharplipinletduringsubsonic,operation(e.g.,tske-off,landin
11、g,orcruising),andsomecompromiseo-fthedesignmaybenecessarytoinsuresatisfactoryover-allperformance. -.Oneofthepurposesofthepresentinvestigationwastostudysomeoftheeffectsoflipbluntnessandprofileonthecharacteristicsofaninletatzeroandlowsubsonicspeedsandforinletmassflowsfromzerothroughchoking.A bodyofrev
12、olutionwitha removable,circularnose-inletportionwasselectedfortheinvestigation.Thelipprofilestestedincludeda sharplip,fiveliyswithcircular-arcprofilespro-vidingcontractionratios(theratiooftheareaencompassedbytheleadingedgeoftheinlettotheminimuminletarea)ofapproximately1.0$,1.08,1.16, 1.24, and2.33,
13、smdtwoliswithellipticalprofilesprovidingcontractionratiosofapproximatelyl.d and1.18.Inthecaseofidealpotentialflowabouta lipoffinitethickness,two-dimensionaltheory(ref.1)indicatesthatthelipsuctionforceformass-flowratioslessthan1.0isexactlyequaltothecalculatedaddi-tivedragoftheenteringflow(refs.2 and)
14、. Anadditionalphaseofthepresentinvestigationwasthemeasurementofbodydragandofthepressuresontheexternalsurfaceofthebodywithdifferentlipsinordertomakea comparisonoftheincrementsofbodydrag,lipsuctionforce,andcalculatedadditivedragresultingfroma changeofmass-flowratio(formass-flowratiosbelow1.0).Theinves
15、tigationwasconductedinoneoftheAmes7- by10-footwindtunnelsfora rangeoffree-streamMachnumbersupto0.330.Boththeangleofattackandangleofyawwere.NOTATIONAAFThefollowingsymbolsandsubscriptsareusedinthisreport:area,Oqftmsximumfroda areaOftestbody,0.785sqft“.Provided by IHSNot for ResaleNo reproduction or ne
16、tworking permitted without license from IHS-,-,-NACATNwa. %DDa%fEhMM=a71M=.mmonl*PPrvxY1.Y. P3170amplitudeoftotal-pressuredragcoefficient,$Fdrag,lbadditivedrag,lb3fluctuations,lb/sqfttotaldragmeasuredbythestraingage,minusthesealtareforce,lbfrequencyoftotal-pressurefluctuations,cpstotalpressure,lb/sq
17、ftradialdistanceinMachnumberaverageinletMachfromwallofinlet,in.number,calculatedassumingentiremeasuredtotal-pressureloss(a diffusertotal-pressureratioI= of0.98wasthencalculatedusingequation(l).(Ifthistotal-pressureratio,0.98,appliesatchnklngregardlessofthelipshapeorfree-streamMachnumber,themajorityo
18、fthetotal-pressurelossesmeasuredatthecompressor-entrancestaiionmusthaveoccurred.attheliporintheconstant-areainletportionoftheduct.)- Withtheassumptionofa constantdiffusertotal-pressureratioofO.%, anyreductionof MS from0.455canbeshownbyequation(1tocorrespondwitha reductionofinletMachnumberfrcm1.0. In
19、thecaseoflipO,forstaticfree-streamconditionsaninletMachnumberof0.69correspondstothechoking ofo.koand,frcmfigure6, thechokingvaluesof m=/m*andH=/ canbefoundtobeabout0.75and0.832(i.e.,0.816/0.98),respect.ive.Thesevaluesofchokingmass-flowicalratioandthetotal-pressureratioareh contrasttothetheoret-choki
20、ngvaluescalculatedinreference4:ml HI= = 0.79m*%Thelowerchokingmass-flowratiomeasuredinthepresentinvestigation,0.75,isthoughttobeanindicationoftheextenttowhichtheactualinlet-flowphenomenadifferfromthoseassociatwiththetheory.Theinequalityoftheeerimentalchokingmass-flowratioandinlettotal-pressureratioa
21、risesbecausethecorrespondingaverageinletMachnumberwas,asshownabove,lessthan1.0. Thecontinuityequationasusedinreference4maybewrittenProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-10anditcanbeseenthatNACATN3170onlywhen Ml=1.0. Theseequationsshouldbeap
22、plicableregardlessoflipshape.Fromequation(1)with HEl = 0.98 andanassumrxlinletMachnumberof1.0,M= wouldbe0.455(asindicatedbythedataoffig.6 forthebellmouth),andthecorrespondinginlettotal-pressureratioH=/ wouldbenearlyequaltothechokingmass-flowratiom=/m*.Thecompressor-entrancelhowever,thecurvesareconsi
23、stentinindicatingtheoccur-renceoflarge-amplitudelow-frequencypressurefluctuationswhichmaybeoftiportanceformassflowsnearchokingfortheinletwitheitherofthetwolips.Theamplitudesofthefluctuationswereasmuchas15percentofthefree-streamtotalpressurewitha frequencyoflessthan20cyclespersecondwhentheinletwascho
24、ked.Noattemptwasmadetocalculatetheextenttowhichtheseeffectsmaybeattributabletotheresonantcharacteristicsoftheducttested.Pressuxestudiesintheinletportions.-Theresultsofstatic-andtotal-pressuresurveysatseveralaxialstationsintheinletportionforlipsOand16Rfora free-streamMachnumberofzeroarepresentedinfig
25、uresU(a) and12(b).ForlipO,surveysexeincludedfortwomassflowsbelowchoking( = 0.30and0.36),whileforlip16R,surveys=e included-foronemassflowbelowchoking( =0.38),.andforthechokedconditionwith = 0.46.Thecorrespondingvaria-tionsoflocalMachnumber,calculatedusingtablesof Mversusp/H(ref.5)arealsoincludedinfig
26、ure12. Fortheregionswherethe.localflowwassupersonic,thelocaltotalpressureswerecorrectedfortheeffectsoftheshockwavehowever,sincelips16Rand18Eprovidedsimilarcontractionratios,itwasassumedthatthevariationoftheadditive-dragcoefficientwithmass-fluwratiowasaboutequalforthetwolips.Thesharpbreaksinthecurves
27、of CD,o-t,whicharerepeatedinthecurvesofexternal-bodydragcoefficientinfigure19,arebelievedtocorrespondwiththeoccurrenceo amify nod!Md B*.31 d flwsemumfw hlatalhnun=fmStdim90.0096Q010100DwoIw.oo114.00117001?.0.031%00EM!_=i=amd mdlnolmaftwbdyRat4mSimmml SibvJwc mmamo a5305120 0.140StalloncMbn lImimrd-d
28、ragmknIn md d smgmMud cftimSIdbl Radlu8900 2f)7s15.00 2J1785500 2s2240s3 2.s221.-4.6704.560 Q1 LE_u207B 1.000Zlle Lo3r?ca lD7tl2236 1.15688al StnibmwLlp 16RI1.54 “mend11.44 911.36 1,1128 I“:i I.z c a-“; / f,8 d /, 6/,4/o Io .1 .2 .3 .4 .5Comprassar-an!rance Mach number, M3 A o .1 2 .3 .4 .5BCamprens
29、or -entrance Mach nurmbar, H=(C) = 0.237Fure 5.- Conttiued.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-ruChLoo.96ISmX90-=0. .92a71:.: B8IGzi-.84BOO J .2 .3 .4 .5.Compressor eniraoca Mach numbar, hIB(d) M=2.0I,6Use with scalo AdiI IZI !0-= 1.2 ml.
30、1= /m.Mo0.1 .2 3 .4 .!5.A 0 .1 :2 .3 Z .3BCorapro$sor-entrance Mach a71umber, U=0.330Figure5.-Concluded.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-* , *H“ G-1 ,s0 Is 33 R h in eE_ o 10 E ! bO Bell mouth.76.72.0 .1 .2 .3 .4 .3Comprosnar -entrrrnc
31、a Mach numbar, MB1.0.9.8I“- I0Um with SCOI* A: .70.s 1 iMFt-t-H,6 P y Eclrla BE/m.5k i y.4f d.3 Io.1 .2 .3 .4 ,5A o .1 .2 .3 .4 ,3BComproasor- enlranc* Mach number, M3Figure 6.-e variatioD6oftot-pxeasureratioand mas6-flow ratio withMach number for each OT the Mpsj = O.compressor-entremceProvided by
32、IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-28 NACATN31707z r“0-=zz:a0.iz;!-Free 8tream Mach number, MO(a) LipO.-1.0h 1.6Y,H ,I I4Choking /limit * / -M3=0.44/Fo .1 .2 .3 .4Free-stream Mach number, MO(b) Lip4R.Figure7.- Thevariationoftotal-pressureratio.withf
33、ree-streamMachnumber. ,.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACATN3170 29.00.98.96.64Iz?=0: .90 ,n Choking mlt llmit moz%1- / .88 .66 1.64.82.6079., “ o . .2 .3 .4Free-stream Mach number, MO(c) Lip8R.Chakinqlimit/ M3U(3.440 . 2 .3 .4Free -stram Mach number, MO(d) Lip16R.Figure7.- Continued.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
