1、ikfNATIONALADVISORYCOMMITTEEFORAERONAUTICSTECHNICALNOTE3394LOW-SPEEDINVESTIGATIONOFTHEEFFECTSOFANGLEOFATTACKONTHEPRESSURERECOVERYOFA CIRCULARNosE LET WITHSEVERALLIPSHAPESByJamesR. Bla,ckabyAmesAeronauticalLaboratoryIvloffettField, Calif.WashingtonMay1955Provided by IHSNot for ResaleNo reproduction o
2、r networking permitted without license from IHS-,-,-IQ.9TECHLIBRARYKAFB,NMNATIONALADVISORYCCMMITTEEFORAERONAUTICSI!lllllllllll!llllllllk;Cluhby?s.-TECHNICALNOTE3394LOW-SPEEDINVESTIGATIONOFTHEEFFECTSOFANGLEOFATTACKONNOSETHEPRESSURERZCOVERYOFA CIRCUMRINLIKlWITHSEKERALLIPSHAPESByJamesR.BlackabySUMMARYW
3、ind-tunneltestswereconductedtoascertainthetotal-pressurerecoveryofa circularnoseinletutilizingvariousshapesofinletlips.Thetestswereconductedata free-stresmMachriimiberof0.237withinletflowsrangingfromlowvaluestochokingandatangle:ofattackfrom0tO 25.A shsxpinletliphavingawedgeangleof7-1/2wastestedinadd
4、i-tiontotwocircular-arcprofilesandtwoellipticalprofilesformedwithinthewedgeofthesharplipbycuttingbacktheleadingedgevari-ousSmounts.Itwasfoundthatfora givensmountofcutback,thecir-cumferentialvariationoftotalpressureatthemeasuringstation(thesimulatedentrancetoaturboet-enginecompressor)wasaboutthessmew
5、itheitheranelliptical-orcticular-arc-profilelip;however,theaveragetotal-pressurerecoverycharacteristicswerebetterwiththeelliptical-profilelip.INTRODUCTIONInreference1,theresultsarepresentedofaninvestigationofsomeoftheeffectsoflipshapeonthelow-speedcharacteristicsofcircularnoseinletsatanangleofattack
6、ofOO. Inpractice,thelowsubsonicspeedsandthehighmass-flowratioscoveredinthosetestsareassociatedwiththemoderatetohighanglesofattackoccurringduringlandingortake-off.Thepresentreportcoversanextensionoftheinvestigationreportedinreference1toincludethemeasurementoftheeffectsofangleofattackonthetotal-pressu
7、rerecoveryattheentrancetothesimulatedturbo$et-enginecompressorinthewind-tunnelmodel.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-2 NACATN 3394Thebodyofrevolutionandfiveoftheinlet-lipprofilesofref- E:_erence1wereutilizedinthepresenttests._Thelippro
8、filesincludedthesharplip,twoofthelipswithcircul.-arcprofiles(providing .-.iriLetcontractionratios,thatis,theratiooftheareaencompassedby r.theleadingedgeoftheinlettotheminimuminletarea,of1.16and1.33),andthetwolipswtthellipticalprofiles(providingcontractionratioaof1.08and1.18). Thetestswereconductedin
9、oneoftheAmes7-by10- - “-footwindtunnels.”NCTMTIONThefollowingsymbolsandsubscriptsareusedinthisreport:AHMm%qrvxYaPLoarea,sqfitotalpressure,lb/sqftMachnumber .-mass-flawrate,lV,slugs/seereferencemass-flowrate,pthereasonsforthisexceptionarenotapparent. -.Contourplotsareincludedinfigures9,10,and11toillu
10、stratetheflowchangesatthesimulatedengine-ccnupressorentranceforselectedconditions-fortheinletwiththreeofthelips.Thechsmgefroma sym-metrictoanasymmetricflowconditionwithlip18Eisshowninfigure9wherethecontourplotsforanangleQfattackofl”andmass-flow.ratiosof 1.44 and1.51arepresented.Thedecreaseoftheavera
11、getotal-pressureratioH9/ accompanyingtheflowchangewasnotedpreviouslyinfigure _Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-6 NACATN33944(d). Similarly,theflowchangesaccompanyingthetotal-pressureloss *:.sufferedwithlip33Rbetweenthemass-flowratiosof
12、”1.87and2.08atanangleofattackofXl”(fig.4(e)areillustratedinfigure10. wInfigureI-1,theflowchangesaccompanyingthechokingoftheinletwithlipO at a = 0areshown.Thethreeconditionsincludedcorre-spondwithhighsubcritical,critical,andsupercriticalinletflow(MS=.0.37,0,41,and0.46,respectively).Forthesubcriticala
13、ndsupercriti.calconditionsthelowesttotalpressuresweremeasuredattheouterwalloftheductwith Hz/H.increasingsteadilyacrosstheannularducttothehighestvalues,whichwere.measuredadflacenttothecenterbody-.Nearthecriticalinlet-flowconditions,however,lossesappear.tohaveoccurredinthecenteroftheduct,perhapsasares
14、ultofthe$hockwavesinthecenteroftheinletdiscussedinreference1,orasaresultofatemporarysepso 0 0 2.078 law16R 0.16 2.44 2.238 1,15833R 0.32 4.88 2.398 1.330All dimensions in inchss.CDI Elliptical liD dimsmsicas Y/X= 0.2777) Ii Gwroctiondssignatiar y x B L.E. rotiar contourInterval= O.0. (Thetop of the
15、figurescorrespondsside of the model.)Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-, * * a71 a *a -O” M3=0.27%,64 . 0.989m. HOa =15” M3-O.26mlo=l.63 $“0.978I I Ia m25” td3=().27Ig H3MO-1.61 =0.958Ho(b)LiptiRFigure 7.-Continued.Provided by IHSNot fo
16、r ResaleNo reproduction or networking permitted without license from IHS-,-,-n)oa =0 M5=0.28 a -25” !43- 0.27I El $-1.64% Ho=0.994 contourinterval=O.0. (Thetopofthefigurescorrespondsviththeleewardsideofthemodel.)IProvided by IHSNot for ResaleNo reproduction or networking permitted without license fr
17、om IHS-,-,-a-C? M3=0.48 :! = 2.40% %= 0BEJ2HO(b)LiP l I “a = 15” MB-0.47H32= 2= i contouz interval= 0.025. (The imp of the figurescorrespondswith the leeward side of the model.)U.1ww.!=. ,., ,1Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-. . . contourinterval.=0.0=. (Thetoporthefigurescorrespondswiththeleewardsideofthemodel.)1Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
