1、L1.i,d1Imobx-lIIIbIJAIIII1II1I,1L,i NATIONALADVISORYCOMMITTEEFOR AERONAUTICSTECHNICALNOTENo. 1709INVESTIGATION OF THE EFFECTS OF A NACELLE ON THEAERODYNAMIC CHARACTERISTICS OF A SWEPT WINGJUNDTHE EFFECTS OF SWEEP ON A WING ALONEBy Gerald Hieser and Charles F. WhitcombLangley Aeronautical LaboratoryL
2、angley Field, Va.=U!I!WashingtonOctober 1948. . -. . , . - -. - -s -. . . . . . . . . . . . . . . . . . . . . . . . . -/- .-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TECH LIBRARY KAFB, NMIlumnnllllulllllu014i9bqNATIONALADVISORYCOMMITIEEFORAEROI
3、WJTICSTECBNICALITOI!ENo. 1709INVESTIGATIONOF TREEEEECTSOF A NACELLEON THEAERODYNAMICSTICS OF A SWEFJ!WINGANDTHEEEFECIBOF SWEEPON AWING ALONEBy GeraldHieserendCharlesF.WhitcombAn investigationwas conductedto detemine the effectsof a nacelleon theaerodynamiccharacteristicsof a sweptwiqgep to 0.61thedr
4、agincrementduetothenacellewas lowerforthe sweptconfigurationsthanfortheunsweptconfiguratims.The additionof thenacelleto thewingreducedthe longitudinalstabilityat all sweepangles. Forboththewing aloneandthewing-nacellecofiinatim,a markedincreasein longitudinalstabilityresultedfrompositivesweep,wherea
5、sonlya smallinoreasewasrealizedfornegativesweep(-45) .When thewingwas sweptback or sweptforwazdto en angleof 45,high pressurepeaksandadversepressuregradientsoccurredneartheleadingedgeof thewingat theacutejunctionof thewingendnacelle.- . .- . . . - . -. - - .-,.Provided by IHSNot for ResaleNo reprodu
6、ction or networking permitted without license from IHS-,-,-2#NACA No. 1709IlvTRoDml?IoN.Recentinvestigationshavebeenconductedto evaluatetheeffectsof ue sweepas a meansofreduqingand d.elangtheadverseeffectsdueto compressibiLL*on theaerodynamiccharacteristicsof awing.Oneof theproblemswhicharisesiswhet
7、hermy unfavorableeffectsoccurwhichtendtolessenor canceltheeffectsof sweepwhena nacelleis added.to a swept*. A studyof theeffectsofwing-nacell.einterferenceat low speedson a sweptwingwithvariousnacelleconfigurationsis gtvenjnreference1.Thepurposeof thepresentinvestigationis to determinetheeffectsofa
8、nacelleon theaerodynamiccharacteristicsof a swept* (overa spetirq) and to comparetheseeffectswiththeresultsobtainedfromtheunsweptwingand.nacelle. In tion, weeffectsof sweep.ontheaerodynamiccharacteristicsofa wingaloneere/presented.AnNACA 6-5wing in combinationwitha modifiedW lU bo was testeriin tiee
9、y 16-foothim-speed tuunelatsweepaLes of Oo,45,and -45fora rangeofMachnumberfrom0.13to 0.61. The*alone was testedat sweepanglesof 00,150,30,45, ti -k5for arange ofMachnumberfromO.13toO.70.SYMBOLSAab/2bt/2c.GCrCtcACA.aspectratio (b2/S)speedof soundin air,feetper secondsemispsnofmodel,feetlengthof quar
10、ter-chordlinebetweenrootand tipchords,feet(fig.1)sectionchordofwingparalJ.elto air stream,feetmeanaerodynamicchordmeasuredparaUel to a tipchordof 2.22feet-andhadnogeometiictwistor dihedral.Theairfoilsectionswereperpendicularto thequarter-chordlineof theunsweptwing. Thewingwasmountedasa reflection-pl
11、anemodel,and sweepwas obtained.by pivotingthewingaboutthe-percent stationof therootchord. A clifferentwingtipwas usedfor eachangleof sweepso thatthetipwasparallelto thetunnelair stream. The spanwiselocationsof theeit stationsofpressureorificeswithreferenceto thetntersect+onof thequerter-. chordlinea
12、nd thetunnelwaU are givenin table1. The chordwiselocationsarealsoincluded.Photographsof thewtigmOtea in thetunnelat eachangleof sweepare shownas figm?e2. TableII“givesthedimensionsof thewingat eachane of sweep.ThenacelLeusedwasa modifiedNACAU-l solid.body (nointernalflow)andwasmountedat themidsamisp
13、anso thatitslongitudinalaxiscorrespotiedwiththewingchordline,andthe45-percent-chordstation.-. . . - . - . . “- .Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA NO. 17 5.of thenacellecorrespondedwiththex-percent-chordstationof thewing. Thsnacelle
14、coordinatesare givenin tableIII. Themaxhiumdiameterof thenacellewas 1.18feetml thelengthwas 7.08feet.Pressureorificeswerelocatedon thenacelleat stations3/16inchfromthew- surfaceat theinboardand outboardjuncturesof thew5ngemdnacelle. Orificeswerealsolocated.on thenacellesurfaceintheverticalandhorizon
15、talplanesthroughthelontmU.nalaxisofsymmetry.Photographsof thewingandnacellemountedin thetunnelat sweephowever,no attemptWasmatito correctthedataforpossibleeffectsof leakageat thetunnelwdl. .RESULTSh Dat largersnes, theveloci-componentconceptaentlyhowever,Unwhereas,at k50 sweepforward.the maxiunmlift
16、 coefficientobtainedwas“O.97. At thesesweptconfigurations,forboththewingaloneandthewing-nacelJecwibination,theprogressof stallwas graduel,amdno sharplossof liftwas encounteredup toabout32ane ofattaok.Drag.- Thevariationof dragcoefficientwithliftcoefficientforthe*alone at sweepanes of 0,15,30,45,and.
17、-45ispresent9dinfigure17 forMachnumbersfrom0.20up to themximum tunnelM znmiber(approx.0.70). In general,therangeof liftcoefficientsinwhichthedragcoefficientsremainedlowerfor thesweptwingthanfor theunsweptwingincreasedwithincreasinglbchnmiber. At Mft coefficientsbelowabout0.23,thedragcoefficientof th
18、e450sweptforwardwingwaslowerthanfor the45sweptbackwing. At higherliftcoefficients,thedragfor 45Sweepforwsrdincreasedmorerapidlywithinc?x3as5nglift than for 45 sweepback.Thisdifferenceof increasein*g withliftis amociatedwiththelowerlift-curveslopeof thewingatsweepforward. .Thedragcoefficientwas sligh
19、tlyhigherfor the15 sweptwingthanfor theunswept at allvaluesof llftcoefficientandMachnumber. Apparently,thebenefitsdueto sweepwhichtendedtoreducethedrag(for A = 15)weresmallerat finitevaluesofliftcoefficitithentheadverseeffectsdueto the smalleraspectratioandlowerlift-curveslope. The causeof thedragdi
20、fferenceat andnesr zero liftisnotappsment,but theclifferpnceisrefitlvelyemslllinmagnitude.lh figure 18 thevariationof dragcoefficientwith-lfftcoefficientispresentedfor thewingnacellecmibinationat sweep30, 45, aua -450. The pitching-momentdatafor thewing-nacelleconikhationme showninfigure23 for sweep
21、anglesof Oo,450,and -45amiMti numbersof 0.20,0.40,arUI0.61. me effectofnacee -sweepon theslopeof thepitching-momentcurveis presentedinfigure24at a Machnumberof 0.61. The effectof thenacellewas to reducethestabilityslightlyat allanglesof sweep. Sweepingthewingin thepositivetiection restitd in“amerked
22、.ticreaseof stability-whichwascausedby theoutwardshiftin thecenterof loadaswas shuwninfigure13. At -45sweepthestabiliwas increaseddueto theinwardshiftof thecenterof lad.PressureDistributionsFressuredistributionsof thewing-nacelleinboardandoutlmamljunctures=8 presentedinfigures25 to 27 for sweepan.es
23、of 0,45, and -45 at liftcoefficientsof 0.20and0.40andhch nuiberofapproximately0.60. No adversepressurepeakswere presenton theunsweptcotiiguration.At A = 450, highnegativepressurepeaksandadversepressuregradientsexistedn- theleadingedgeat thetibOaJuncture,whereasat thenegativesweeppositionthesameflowc
24、heracteisticsresultedat theOutbOa junctureneartheleadingedgeof thewing. The criticalMachnumberwas surpassedfor thesweptbackpositionat liftcoefficientsof boti0.20end0.40andfor thesweptforwerdpositionat a liftcoefficientof 0.40. Despitethesesupercriticalpressurepeaks,thenacelledragfor thesweptconl?igu
25、rationsbasedonnacellefrentalareawaslowerthanfor theunsweptconfigurationas is showninfigure20. Apparentlytheprpssurepeakscausedbywing-nacelleinterferenceweretoolocalizedin thel thenatureofwhichwouldrequirea detailedstudy. Thedatain,reference1 indicatethata modificationin thecontourof thenacelleortion
26、whichprotrudesaheatiof the-wingleadingedgetoconfom withtheflowpattefnimmediatelydhfflaof a sweptwingiseffectiveinreduc thepressure. . . . . . - -,pea$sat the juncture./1. - .Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-10 NACATNNO. 1709Figures28 t
27、o 30 showpressuredistributionsonetheupperlowersurfacesin theverticalplaneof spnet of thenacelleforsweepanglesof 0,45,and -45at a Machnumberof about0.60andliftcoefficientsof 0.20andO. For thesweptconfigurationsthepressuregradientsbehindthemaxhmm negativepressuresweremoregradualthanfortheUnsweytConfig
28、uration.In addition,theeffectof thesweepwas to movethecenterofpressureforwardon thenacelle.No extremepressureyeaksoccurr overthisportionof thenacelJ.eforamy of thetestconditions.Pressurecontoursfor theupperand.lowersurfacesof the*alonearepresentedinfigures31 to 42. As would be expected.fromthetieory
29、of sweey,thenegativepressuresonboththeupperandlowersurfaceswerereducedas thesweepwas tireased. Figures31 to 33shuwtheeffectsof sweepon thelocationof thepeakpressuresforaliftcoefficientof 0.20anda Machnumberof 0.61. At zerosweep, thepeakpressureson theuppersurfaceoccurredat aboutthe35-yercent-chordst
30、ationovertheentirespanof thewing. For thewingat 450,thepeakstowardthecard portionof thewingremainedat aboutthe35-percent-chofistation,whereasmum thetiptheyshiftedforwardtotheleadingedge. At A = -450 tie ao the span Ocmea atthe leading edge except for thosenearthetipwhichw6reshiftedslightlyrearward.
31、The effectsof sweepon thespwise dlstmibutionofpeakpressuresarealsoevidentinfigures31 to 33. ThepeaksshiftedOu*a forpdsitivesweepand -a fornegativesweep.Thiseffectis consistentwiththespsmwise-loadingcurvespresentedinfigure13. It isapparentfromfigures32 and33 thatthespsmwisepressuregradiemtat sweepfor
32、wsrdwas greaterthemat sweepback;adsincethepeakpressuresoccurredfartherfOa on thewingat sweep-fOa, thegratienteffecteda spanwiseflowovera greaterportionof thew3ng.Figures34 W 35 presentpressurecontourson thewingat a liftcoefficientof 0.20anda -ch numberof 0.61for sweepanes of 150and 300,respectively.
33、Thesefiguresshowat thepeakpressuresontheper surfacewereshiftedprogressivelyoutboerdas thesweepanewas increased.lhaddition,increasingthesweepreduced,themagnitudeof thepressureson boththeupperandlowersurfaces.A comparisonoffigures31 and34 shuwsthatthespanwisepressuregradientalongthelrailingedgefor the
34、0 and15 sweeppositionswereof approximatelythesamemagnitudebut oppositein slope. sfactindicatesthatthespenwiseflowin theboundaryUyer shouldbeof aboutthe samemagnitude.Pressurecontoursfor thewingat A = 0, 45, -45 foraliftcoefficientof 0.20andaMach nuniberof 0.20areresentedinfigures36 to 38. A comparis
35、onof thesepressureswiththoseoffigures31 to 33 indicatesthata changeinMachnuuiberfrom0.20to0.61haano appreciableeffecton thepressurecontours. .-. ._=. .-.- _ - -:“;.-.-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MACATN No. 1709 11.The contoursofsw
36、eepbaokfora llftfigures39 end 40 are shownwiththewingat,45coefficientof zeroandch numbersof 0.20= 0.61,respeotive Theuppersurfacepeaksacrossthespan“occurredbetweenthe 45- and x-percent-chordstationsat bothMachnumbers. Increasingtheliftcoefficientto 0.40shiftedthepeakpressureson theuppersurfaceto the
37、leadingedgeof thewing(figs.41 and42).Figures43 to Z shuwthepressurecontoursfor thewing-nacelleoonibination.Thesedataarepresentedfor thesameliftcoefficients,Machnwibers,amd sweepanes as are givenfor thewingaloneInfigures31 to 33ad 36 to 42. AS was previous- showninfigures26M 27, high localized pressu
38、re peaksexistedat theleadingedgesofthewing-nacellehiboardncture of thesweptbaok* end thewing-nacelleoutboardjunotureof theptfa wing. In general,thelinesof constantpressureonboththeuer andlowersurfacesatthese$mOturesweresoalteredbecauseof thewing-nacelleinter-ferencethattheybecemenormalto theair stre
39、am. Thisfaotindioatesthatin thevicinityof the ,Wnoturewherethecriticalwessures wereexceeded,theresulthg shock-alsooccurredin a ectiotheairstream;therefore,thelossthroughtheshockwaswouldhavebeeneqerienoed.had theshockbeenobliquetofluw.Thepressurecontourson the 45 sweptbackwingwithnmmal togreaterthan&
40、e anoomingvertical platei.mdbaj fw a liftcoefficientof 0.40d a Maohnumberof 0.20,arepresented.infigure53. ApparentlytheplatesweresomewhateffectiveInreduoingtieextremelocalizedessure peaksat theleadingedgenesrthetip,but theydidnotalterthepressurepatternon thetraiportionof *e wing.VisualObservationofF
41、lowCharacteristicsTheflowpatternsin theboundaryar on thewingaloneandthewing-naceld.econibtionfor sweepsnglesof 0,450,and -45atvariousanglesof attaokandMachnumbersarepresentedh figures54-to 57.Thesep&tternewereinterpretedfromtuftstudiesof theflowoverthemodel. Withthewingat A=Oo and A=45 qnd.angles of
42、attaokfora liftcoefficientof 0.40,theadditionof thenacelleoaueedaslightdeviationof theflowin theimediat6vicini of thenacelle* (fi& a71 * 55)=Fiwe 56 showsthat,at tiesamelut coef-ficient,theadditionof thenacelleto theswept!?ozwardwingresultedinno detectabledeviationin theflow. n addition,figures55and
43、 56indioatethatneitherthedistortionof theairstrea dueto thevelocitycomponents.whiohresultfrcmsweepnor thespanwl.seflownearthe*ailingedgewas alteredby thepresenoeof thenacelle.a71-. .-. . - . -. ._. _.,.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
44、12 NACA NO. 1709.Comparisonsof theflowpatternsoverthewingand thewing:nacelleccmMnations=8 presentedin figure57 at geometricanesofattackof 180,22,and200for sweepan.esof 0,45,and -45,respectively.At A = 0 theadditionof thenacelleappreciably “ticreasedthesreaoverwhichunsteadyflowoccurred.,whichindicate
45、sthata substantieJ.lossof liftresulted.Thepatternsfor thesweptconfigurationsshowthatthepresenceof the.paceld.ehadverylittleM?luence on thefluwcharacteristicsoverthewinganddidnotappreciablyincreasetieareaof unsteadyfluw. Theresultsshownbythesepatternsserveto suemmt thelifttitsoffigure16.Theflowpatter
46、noverthewing.at450sweepbackandat a geometricae ofattackof 6withtheverticalplatesmountedon theuppersurfaceispresentedinfigure58. Thispatte?.mshowsthattieplateswererelativelyineffectiveinreducingtheboundary-lapr samwlseflowoverthe portionof thewing. Visualobservationsoftuftsnunzntedon thesurfacesof th
47、eplatesindicatedthattheairflowedupwardon theinboardsurfacesof theplates&ad&mmward on thesurfacesfacingoutb-.Figure59 presentstheflowpatternsoverthewingat A = 45 wiihthestraightand curvedvanesinstalled.Thed.lstortionof flowam tosweepbackwasreducedimetiately-outboardof thestraightvane,whereastiecurved
48、vanehadno noticeableinfluenceon thepatternof flow.CONCIIOlW /.Therekultiof an investigationto detezninetheeffects.ofanacelleon theaarodpamiccharacteristicsof a sweptwingend theresultsof theeffectsof sweepon theaerodynamiccharacteristicsof thewingaloneledto thefolwtng conclusions:1. The eqerimentalvariationofwinglift-curveslopewithsweepane is in goodagreementwiththetheoreticalvariationup to 30sweep. At greatersweeps,however,theveloci-componentconceptapparentlyunderestimatestheeffec
