1、THE DRAGOFFORAERONAUTICSTECHNICALNOTE2941FINITE-LENGTHCYLINDERSDETERMINEDFROMFLIGHTTESTSAT HIGHREYNOLDSNUMBERSFORAMACHNUMBERRANGEFROM0.5TO 1.3ByClementJ.WelshLangleyAeronauticalLaboratory.,ngleyField,Va.WashingtonJune1953Provided by IHSNot for ResaleNo reproduction or networking permitted without li
2、cense from IHS-,-,-TECHLIBRARYKAFB,NMllllllllllggpp=NATIONALADVISORYCOMMITTEXFORAERONAUTICSTECKNICALNOTE29$1THEDRAGOFFINITE-LZNGTHCYLINDERSDETEBMNZDFROMFLIGHTTHISATHIGHREYNOLDSNUMBERSFORAMACHNUMBERRANGEFROM0.5IO1.3ByClementJ.WelshSTJMMARYResultsofafree-flightinvestigationtodeterminethedrsgofcircular
3、finite-lengthcylindersarepresentedforaMachnuuiberrangefromabout0.5to1.3.Finenessratiosofthecylinderstestedwere15,30,and60. Resultsofpreviousexpertientaltestsofcircularcylindershavinginfinitefinenessratiosareincludedinthispaperforcomparison.Forsupersonicspeeds,thedragofcirculsrcylindersislargelyinde
4、pendentoffinenessratioandReynoldsnuuiber.AtsubsonicMachnumbers,thedragoffinite-lengthcylinders(finenessratiosofabout60andbelow)Increasesastheirfinenessratiosticrease.INTRODUCTIONBecauseoftheinterestthatexistsinthedragofcirculercylindersandbecauseofthelackofexperimental.dragdataforcylindersforMachnun
5、ibersintheregionofunity,theNationalAdvisoryComnitteeforAeronauticshastie somefree-flightteststodeterminethedrsgofcircularcylindersoffinitefinenessratiosathighReynoldsnumbers.Cylindershavingfinenessratiosof15,30,end60weretestedinfreeflightoveraMachnuderrsmgefrom0.5to1.3;therangeofcorre-spondingReynol
6、dsnuniberbasedoncylinderdiameterwasfrom1.25x 105tO 7.25x lo. ThecylinderswerenmuntedontestbodiesinsuchamannerastominimizeInterferenceeffects.ThetestswereconductedatthePilotlessAircraftResesrchStationatWallopsIslsnd,Va.“8a71Provided by IHSNot for ResaleNo reproduction or networking permitted without
7、license from IHS-,-,-2 NACATN2941Theresultsofthesetestsarepresentedhereinandarecomparedwithpreviouslyobtainedexperimentaldragdataforcircularcylindersofinfinitelengths.SYMBOLSbT total-configurationdragcoefficientbasedonthetest-bodyfrontalareaQ cylinderdragcoefficientbasedoncylinderfrontalareaM Machnw
8、iberR Reynoldsnuniberbasedoncylinderdlsmetern finenessratio,LL lengthofcylinder,in.D diameterofcylinder,in.MODELSANDTESTSThegeneralarrangementforthethreetestconfigurationsusedinthisinvestigationisshowninfigure1,andaphotographofatypicalmodelisshownasfigure2.Thebasicbodyonwhichthecylindersweremountedw
9、asasimplyconstructedcircullsr-cylindricalwooden.bodyhavingaspecialfinassenibly.Therectangularendplatesmountedontheendsofthehorizontalfinsprovidedthenecessarystabilizingareaintheverticalplane.Thecylinders,inturn,weremountedontheend”platessothatessentiallyhalfacylinderwasmountedoneachendplate;theleadi
10、ngedgesoftheendplateswerebeveledonthesideawayfromthecylindersinordertominimizetheflowdisturbancesoverthecylinders.Thefinassenililyandcylinderswereconstructedofsteel.Themodelswerepropelledbyatwo-stagerocketarranthesecondstagewasa3.2-inchaircraft-rocketcontainedwithinthemodel.-Provided by IHSNot for R
11、esaleNo reproduction or networking permitted without license from IHS-,-,-NACATN2941TestdatawereobtainedbytheDopplerradarinreference1. Infigure3,theReynoldsnumber3techniqueasdiscussedduringflight,basedoncylinderdiameter,isplottedagahowever,itisbelievedthatitwouldapproachinfinity.Thevariationofthedra
12、gcoefficientswithMachnuuiberforthecylindersofthepresenttestsformsabandwhich,at M =0.7,centerssroundapproximately1.2,increasestoabout1.9at M = 0.95,andthendecreaseswithincreasingsupersonicspeedstoapproximately1.5atM= 1.3. Thecoefficientstithinthisbandshowthatthedragofcylin-dersincreasesastheirfinenes
13、sratiosincreaseatsubsonicMachnumbers.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-4 NACATN2941At-supersonicspeeds,however,thewidthofthebandofthecoefficientshasdecreasedandnoapparenttrendofthedragcurvesrelativetoeachotherexists;further,thesupersoni
14、cdragcoefficientsdeterminedbyStantonandBusemannforcylindersofeffectiveinfinitefinenessratios,endatReynoldsnumbersmuchlowerthanthoseof%hepresenttests,appeartobeconsistentwiththecoefficientsofthepresenttests.Fromthecomparativeagreementoftheresultsofthesetests,itappearsthatcylinderdragcoefficientsarela
15、rgelyindependentofReynoldsnuniberandfinenessratioatsupersonicspeeds.(AlthoughtheReynoldsnuderoftheBusemanntestisnotlistedinref.3,Dr.A.Busemann,whoisnowattheLangleyLaboratory,confirmedthathistestwasmadeataReynoldsnumberofapproximately50,000.)Thedipexistinginthedrag-coefficientcurvesforthecylindersoff
16、inenessratiosof30 and60 atapproximatelyM=0.825maybetheresultoftransitionfromlsminartoturbulentflowaroundthecylinders;thisresultisconsideredfurtherinthediscussionoffigure7. Similardipsincylinder-dragcurveswereshowninreferenceJ-whereanunsuc-cessfulattemptwasmadetocorrelatetheoccurrenceofthedipswithwak
17、e-widthvsriation.Thelackofadipinthedragcurveofthecylinderhavingafinenessratioof15maypossiblybe“explainedbymorepre-dominantendeffectsexistingforthislowerfinenessratio.a71 a14a15uThedragcoefficients(basedoncylinder_fYontalarea)forthecylinderstestedareshowninfigure7plottedagainstReynoldsnumber.Alsoshow
18、ninthisfigure,forcomparativepurposes,srepreviouslyobtainedexperhentaldragcoefficientsofcylindersflromreferences5to7. TheresultsforthetwolsrgercylindersofStackstests(ref.6)veryclearlydefinethepronouncedeffectsonthedragcoefficientsofcylinderswhentransitionfromlsminartoturbulentflowoccurspriortothecrit
19、icalMachnuuiber.Whenthiseffectisrememberedandthetrendoftheinitialportionsofthedragcurvesof“thepresenttestsisnoted,itappearsthatthedipsinthedragcurvesforthetwocylindershavingthehigherfinenessratiosmaybeattributedtotheoccurrenceofthecriticalMachnumberfollowedbytransition,thecompressibilityeffectsbeing
20、predominant.a71AtsubcriticalMachnumbersandReynoldsnuribersthedragofthecylinderhavingafinenessratioof60agreeswiththatforcylindersofinfinitefinenessratios(seefig.7);thus,whendeterminingdrsg,cylinderswithfinenessratiosofabout60orgreatermaybeconsideredtobeofinfinitelength.Provided by IHSNot for ResaleNo
21、 reproduction or networking permitted without license from IHS-,-,-NACATN2941 5CONCLUSIONS*Free-flighttestsinaMachnuniberrsugefromabout0.5to1.3ofs circulsrfinite-lengthcylindersandtheresultsofpreviousexperimentaltestsofcirculsrcylindershatinginfinitelengthsleadtothefollowingconclusions:1.Dragofcircu
22、larcylindersatsupersonicspeedsislargelyinde-pendentoffinenessratioandReynoldsnumber.2.AtsubsonicMachmmibers,thedragofftiite-lengthcylinders(ftienessratiosofabout60andbelow)increasesastheirfinenessratiosincrease.LangleyAeronauticalLaboratory,NationalAdvisoryCommitteeforAeronautics,LangleyField,Va.,Ap
23、ril3,1952.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACATN2941REFERENCES *1.Thompson,F.L.: FlightResearchat!IhnsonicandSupersonicSpeedsWithFree-FallingandRocket-PropelledModels.SecondInternational RAeronauticalConference(NewYork),Inst.Aero.Sci.
24、Inc.,1949,pp.582-596.2.Stanton,T.E.: OntheEffectofAirCompressiononDragandPressureDistributioninCylindersofInfiniteAspect-Ratio.R.D= 1 inch.4.0n D,in.15 1-30 1 :/3.2 .60 1/2 / SiC body /2.4 /CDT1.6.80. /i. .6 .7 .8 .9 1.0 1.1 1.2 1.3 1.4 1.5 ,MFigure7.-Variationoftotaldragcoefficients,basedonbodyfro
25、ntalarea,withMachnumberforthecylinderconfigurationsinvestigatedandforthebasictestbody.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-4 .5CDZ.48.01.61.8.8.40.5 .6 .7 .0 .0 1.0 1.1 l.e 1.3 1.4 1.6 1.6 1.7 1.0 1.9 e.o e.1MFiguze 6.- Variation of cylind
26、er drag coefficients,based on cylhierfrontal area, with kiachnumber for the cylinder configurationstested. Also shown are two experimentally determined supersoniccylinder drag coefficients of previous investigations.Provided by IHSNot for ResaleNo reproduction or networking permitted without license
27、 from IHS-,-,-2.1.CD.8 1 I I I I I I IStack (ref. 6)Presen%testst-t-1 n D, in. D, in.15 1 4 1/2.4 30 1 o-. :160 1/2 “%! I n l I ! 1“105 04 105 106RFigure 7.- Variation of the cylinder drag coefficients, ba6ed oncylinder frontal area, With Reynolds nur!iberfor the cylinders ofthe present tests end for infinite length cylinders of previousinvestigations. (Symboled pointa do not represent experimentaltest points.).40-.1Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
