1、uLi3“,I,11a71J,TECHNICAL NOTE 3675THE EFFECTS OF COMPRESSIBIIXCYON THE UPWASH AT THEPROPELLER PLANES OF A FOUR-ENGINE TRACTOR AIRJ?LANECONFIGURATION HAVING A WING WITH 40OFSWEEPBACK AND AN ASPECT RATIO OF 10ByArmandoE. LopezandAmes AeronauticalMoffettField,JeraldK. DicksonLaboratoryCalif.WashingtonJ
2、tiy1956. . . . . . . . . . . -4. . . . . . . . . . . . . .-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TECHLIBRARYKAFB,NM.A.“lMIIIlllNATIONALADVISORYCOMMITTEEFORAERONAUIIC$00bb363TECHNICALNOTE3675UPWASHATTHETHEEFFECTSOFCOMPRESSIKCLITYONTKEPROPELL
3、ERPIANE3OFA FOUR-ENGINETRACTORAIRPLANECONFI?WRATIONHAVINGA WINGWl?IH“ OF-RACK ANDANASPECTRATIOOF101ByArmandoE.LopezandJeraldK.Dicksons-YAninvestigationhasbeenconductedinwhichupflowanglesweremeasuredalongthehorizontalcenterlinesofthepropellerplanesofasemispanmodelrepresentingamultienginedairplanewith
4、tractorpropel-lers.Thewinghad“ ofsweepback,anaspectratioof10,andataperratioof0.4. TestswereconductedatReynoldsnumbersof2,k,6,and8milltonatlowMachnumbers,andaReynoldsnumberof2millionatMachnumbersfrom0.25to0.92.Inaddition,theupflowwasmeasuredwiththenacellealonetoevaluatethetheoreticalmethodforpredicti
5、ngtheupwashinducedbythenacelle.ThetestswiththenacellealonewereconductedataRemoldsnumberof4millionataMachnumberof0.123,andataReynoldsnumberof2millionatMachnumbersfrom0.60to0.92.TheresultsindicatethatforMachnumbersupto0.60theupwashanglescanbepredictedaccuratelybytheavailabletheoreticalmethods.AtMachnu
6、mbersabove0.60theexperimentalvalueswerelessthanthosepredictedbytheoryandthisdifferenceincreasedwithincreasingMachnumber.INTRODUCTIONassociatedwithhigh-speedpropeller-drivenair-aerodynamicloadswhichimposevtbratorystressesalargeportionoftheseoscillatingaerodynamicAnimportantroblemplanesistheoscillatin
7、gonthepropellers.Sinceloadsresultfromnonuniformity-andangularityoftheflowenteringtheSupersedesNACARMA53A30abyArmandoE.LopezandJeraldK.Dickson,1953. . . .Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-2 NACATN3675propeIlerplane,studieshavebeendirecte
8、dtowardanunderstandingofthefactorsaffectingtheair-streamcharacteristicsinthisregion.Itappears,onthebasisoftheinvestigationreportedinreference1,thatsatisfactoryesttiatesofthefirst-ordervibratorystressesinapro-pellercanbemadeiftheupflowanglesalongthehorizontalcenterlineofthepropellerplanesareknown.Asi
9、defromitsimportanceincon-nectionwithpropellerstressproblems,knowledgeoftheseupflowanglesisalsousefulinestimatingthemagnitudeofthepropellernormalforceinconnectionwithlongitudinal-stabilianalyses.Theinvestigationsreportedinreferences2,3,and4haveproducedtheoreticalmethodsforprectingtheseupflowangles.Ho
10、wever,nopreviousexperimentalveri-ficationisknownf?rMachnumbersabove0.20. .TheinvestigationwasconductedintheAmes1.2-footpressurewindtunneltomeasuretheupflowanglesalongthehorizontalcenterlinesofthepropellerplanesofamodelrepresentingamultienginedlong-rsnge,high-speedairplanethroughoutawiderangeofsubson
11、icMachnumbers,andtocogparethemeasuredrateofchangeofupwashanglewithangleofattackwiththatpredictedbymethodsofreferences2,3,and4.WI!ATIONAAuab/2cCt%c2iMupflowangle,angleoflocalflowatthehorizontalcenterlineofthepropelZerplane,measuredwithrespecttothethrustaxisinaplaneparslleltotheplaneofsymmetry,u+ e +7
12、degupflowsngleuncorrectedfortunnelinducedupwash,degmean-linedesignation,fractionofchordoverwhichdesignloadisuniformsemispanofmodel,ftlocalchordofwingparslleltoplaneofsymmetry,ftwingchordperpendiculartothereferencesweepline,ftliftcoefficient,lift/qSdesignsectionliftcoefficientfree-stresmtiee-stream.
13、Mathatis,theprobewasrotatedaboutitsaxistothepositionwherethepressuresatthetwoorificeswereequal.Theangularpositionoftheprobewasindicatedasa counterreadingbytheresponseofaninstrumentreactingtothedis-placementofthedifferentialtransformerattachedtotheprobeactuatingmechanism.Staticcalibrationoftheinstrum
14、entindicatedthattheangulardisplacementoftheprobecouldbedeterminedwithanaccuracyofio.03. additiontothestaticcalibration,itwasnecessarytoestablishtheangularpositionoftheprobeforzeroupflowangleofeachpairoforifices.Thiswasaccomplishedwiththeprobeandspinnermountedinauniformstreanatzerosingleofattack.With
15、thecounterreadingforzeroupflowanglethusestablished,thecounterreadingsforbalancedpressuresacrosseachpairoforificesobtainedinthetestswiththeprobemountedonthecompletemodel(fig.3(a)andonthenacellealone(fig.3(b) could“beinterpretedintermsofupflowanglebymeansofthestaticcalibration.Theestimatedover-sll.lac
16、curacyoftheupflowanglemeasurementsisA0.2forthetestsatthelowestdynamicpressureandN.l” atthehighestdynamicpressure./. . -.- _Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACATN3675 5CORRECTIONTODATACompleteModelThecorrectionstodatafortunnel-wallinte
17、rferenceresultingfromliftonthemodelwereevaluatedbythemethoddescribedinreference6.Thecorrectedangleofattackwasa = ag + 0.377CLThiscorrectiontotheangleofattack,whiahwasusedonlyfortheliftdatayresentedh figure4,isbaseduponthetumnel-tiducedupwashatthequarter-chordlineofthewing.Sincethetunneltiducedupwash
18、atthepropellerplaneswasnotequaltothatatthequarter-chordlineofthewing,a correctiontothetotalupflowanglewascalculatedbythemethoddescribedinreference6 andwasusedinthedatapresentedinfigures5and6. ThecorrectiontothetotalupflowangledifferedlittleforeachpropellerplaneandwasessentiallyunaffectedbyachangeinM
19、achnumber.ThecorrectedangleofupflowwasA=:. ,/ .“%.,(b) The isolatednacelle with the probe installed.Figure 3.- Concluded.w2LnIProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-1.4/.21.0,8.2-.4n probeoff wok on inner nocelle .G probe on oufer nffcelle 4
20、04812 /6 20 for M= 0./23, R“ +OOQOOOAngle of attack, Q, degFigure 4 . Vorhtlon of lift coefficient with ongle of utfack.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACATIT3675 21.2820+-,vI 7 /3.860I I I L.I u . . .0 /.88D 3-48/2/6d, 1 14-AA 5.94
21、i) I I I I I I I I I I I I 1, I 1 1 I 1 I Io/0.20 .30Frocflonof(ujM=O./23,Figure5.-Uphw angles.40 .50 .60 .70 .80semispm,R“4,000,000otvoriousanglesofattack. _ _ .- . . _ _ _f - .Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-22 NACATN367P28 4/ A24
22、I Ab20 P &4 ab. x /9.80T/6 7 7 IL /Z823 , m /2 g b p /5.840 L/3.86f8 *“ * p/.88P P34 1& F ),9.900X7. w.R? Z92).1ti30 i* A “ 5.94-4 6“ 3.96m 1+/ /.98d IL-8 )( , 0L/.98-/2 Y d It I I 1/6 mo ./0.20 .30 .40.50 .60 .70.80Fructlonofsemlspm,C)M= O./65,R=8,00000Figure5.- Continued.-. -. . Provided by IHSNot
23、 for ResaleNo reproduction or networking permitted without license from IHS-,-,-24 NACATN3675.20/6+ 88/2-/6o ./0 .20 .30 . .50 .60 .70 .80Figure5.- CoAfnffe.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACATN 3675 25+-28 4A24 b Itk .420 . a /6%.+
24、/2 4 1 z /5.840_a711%“/3.860-8/l.88s L&4 v P “9.90w T ywh ? ? Z92/.J30 i a A* 5.94-0“ =$. -4 3.960m . m /.98-8 (q + odL(d /.980-/. d. r*-.fY d-/6 To ./0.20 .30 .40.50 .60:70.80Froctionofsemlspun,eM=0.25,J?=2,00CjOO0Figure5.-Continued. -. . _ _._.Provided by IHSNot for ResaleNo reproduction or networ
25、king permitted without license from IHS-,-,-26 NACATN3675282420/6+-I 1 1 , “ , 1 1 1 / w Ir SIN, , .1 I I I 11- 1 , 3.960.m _ .“& /.98 _JQ. .a(q30a71 # 3 /.98 0 Ib * I I. . &.I Iyo JO .20 .30 .40 .50 .60 .70 .80Fmctionof semispm, (I) M= 0.90, R= 2,000,000Figure5.- Continued. - . - Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
