REG NACA-TN-2941-1953 The drag of finite-length cylinders determined from flight tests at high Reynolds numbers for a Mach number range from 0 5 to 1 3.pdf

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-,-,-