1、.TECHNICAL NOTE 2894CALCULATIONS OF UPWASH IN THE REGION ABOVE ORBELOW THE WING-CHORD PLANES OF SWEPT-BACKWING-FUSEIAGE-NACE LLE COMBINATIONSBy Vernon L. Rocjallo and John L. McCloud, IIIAmes Aeronautical LaboratoryMoff ett Field, Calif.WashingtonFebruary 1953. . . . . . . . . . =_ ,. _ . ._ .+. ._
2、._- -.,- . . .-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-IGull LJBR/lRYKAFB, NMiIQ IUIUMIIIIIIIIIIIIUH00b5787NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS -TliCHNICATNOTE 2894CALCULATIONS OF UPWASH IN THE REGION ABOVE OR -.BELOW THE WING-CHORD PL
3、ANES OF SWEPT-BACKWING-FUSELAGE-NACEILECOMBINATIONSBy Vernon L. Rogallo and John L. McCloud,IIISUMMARYA procedure has been developed for predicting the upwash compo-nents of the upflow angles in the region above or below the wing-chordplanes of qept-back wing-fuselage-nace13ecombinations. This proce
4、dureentailsmodifications to the methode given in NACA TNs 2528 and 2795,for predicting induced upwash angles.Comparisons of prected and the wing upwash of reference 3 is onlyapplicable in the reon of the extended wing+hord plsme.It is the purpose of this report to present modifications to theex name
5、ly,the total upwash angle at a point is assumed equal to the sum of theupwash angles induced by the wing, nacelle and fuselage. The wingupwash is due to the wing lift end is calculated.using lifting-line orlHtingface tkory and the fuselage and.nacelle upwash are calcu-lated from potentiel flow equat
6、ions for an infinite cynder end semi-infinitebcxiy,respectively.Wing-Muted UpWash .,Although the liftingne thsory used in reference 2 is applicablein regions ove or below the winghord plane, it is not directlyapplicableto swept wings. The simplified lifting-surface methd ofreference 3 enables calcul
7、atbn of the upwash ahead of wings of arbi-trary plsn form, t only in the wing-chord plane. ThnE to detetinethe upwash in regions other than the wing-chord plane for wings ofarbitraryplan form, it is necessary to extend or modify the existing.methmis.For simpcity, the Ilfting+mrface method of referen
8、ce 3 has beenmaiified The mdificatim is based on the assumptionthat the verticalvariation of upwash from a wing is similar to the vertical variation ofupwssh from a horseshoe vortex. For low Mach numbers, the bound vortexhas the same sweep as the wing quarterhord line, snd lies in the wing-chord pla
9、ne.g For a value of q and T/9, the vertical variatim ofupwash due to the horseshoe vortex is readily found from the followingequation which correspondsto equation (34) of reference 4.SForhigh Mach nuaibers,the horseshoe vortex should have a sweepangle given by tan = (tanA)/P in accordancewith thePra
10、ndtl-Glauert rule. . . . .,. . . _. . . . . .Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-,.&”&II-*2 - &-. +211tm+ _T/p( t.EDlT/)2+ #CCB9 l (T/f3tanAp+2%J+4 -*JJI”P+(W) mlvb+(1-q)tanff!l +(l+q)+! .-JProvided by IHSNot for ResaleNo reproduction or
11、networking permitted without license from IHS-,-,-6 NACA TN 2894If the upwash at a point above or below the winghord plane is expressedas a percentage of the umash in the wing-chord plene, this percentagemay be used to detemine the wing upwash at a correspting q T/jand distance above or below the wi
12、ng+had plane. To show a typical .example, the upwash expressed.in this manner is presented in figure 1for a o swept4ack horseshoe vortex system.Fuselage-InducedUpwashIn the previous applications of the methcds of references 2 and 3,the horizontal center lines of the propeller planes were coincidentw
13、iththe median plane of the fuselage. In order to calculate upwash at thehorizontal center line of propeller planes which are not coincidentwiththe fuselae medien pleae, the methcd used in references 2 and 3 must beextended. The velocitybaiy longitudinal -S)the following sketch.c&ponents (in a vertic
14、al plane parallel to theof the flow about en inclined bcdy are shown in/%Yb /From the geometry of the velocity componentsW+AW+Aw-$r W()+#td+=u+m=u= +VWU=+*therefore, since w/u = tan ,(1)(2) . . - - - Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-7N
15、ACA TN2894which for smallIf AW end,angles (ab and ) may be written(3)NJ can he found for any point in space, eb is knownfor that point. Although it is difficult to find these quantities fora finite baly, they are readily obtsined for the infinite cylinder inincompressible flow.For a fuselagewhich ha
16、s a large fineness ratio and extends wellforward of the propeller plsne (at least three maximum mean diemeters),it may be assumed that the fuselage can be represented by an infinitecylinder equsl in diameter to that of the cross setion of the fuselagein the extended propeller plane (see reference 2)
17、. In the case of aninfinite cylinder,Z!U is equal to zero, hence equation 3 becomes(4)To determine the increase in cross-flow velocity, the well.-lmownsource-sink or doublet equations found in most texts on hytmiynamicsexe used. For an infinite circular cylinder in an incompressible flow.=4&(Lw(3W)T
18、The lateral distribution of eb/ab at constant distances above orbelow the median plane of an infinite circular cylinder i-spresentedin figure 2.(5)4The validity of this assumption has not been checked for the case ofcompressible flow.c.- - - .-., . . - . -. -. -Provided by IHSNot for ResaleNo reprod
19、uction or networking permitted without license from IHS-,-,-8 NACATN 2894REstmE3 .To provide experimentaldata for evaluation of the mdified “methcds, surveys were made of the upflow angles at the horizontal centerline of the yropeIler disks for six semispan models with 40 swept4ackwings. The surveys
20、 were made in the Ames ti- by 80-foot wind tunnel ata &h number of 0.13. One of the mcdels is shown mounted in the windtunnel in figure 3. All six models are shown in figure 4. The surveyrake shown in figure 3 consisted of six directionslitot-static tubesmounted at various intervsls along a steel tu
21、be. 5 methai of reference 3, together with the mcdifications included herein, has been usedto predict the upwash angles,which are combined with the geometricangles to obtain the upflow angles for the six models. Comparison ofthe measured and.predicted upflow angles at several locations along thehori
22、zontal center line of each propeller disk is shown in figure 5.Upflow angles are shown for angles of attack of “, 0, 4, 8,and 10. Although not evident from figure 5, the qgeement between themeasured and predicted upflow angles was found to be of the same orderat various points along the horizontal c
23、enter line of the propellerdisks and for the different nacelle locations at a given angle of attack.CONCLUDING RE- A procedure for predicting the upwash component of the upflowangles in the region above or below the wing-chord plemes of sweptiackwing-fuselage+mcelle combinations has been developed a
24、nd evaluated.The accuracy of the upflow angles obtainedby this procedure isconsidered satisfactoryfor use in estimating propeller tibratorystresses.1 Ames Aeronautical LaboratoryNational Advisory CormnitteeMoffett Field.,Calif.,.for AeronauticsNov. 14, 1952REFERENCES1. Roberts, John C., and Yaggy, P
25、aul F.: A Survey of the Flow at thePlane of the Proller of a1950.Twin4ngine Airplane. NACA TN 2192,I 2. Yaggy, Paul F.: A Method forat the Propeller Ylane of aWing. NACA TN 2528, 1951.Predicting tk Upwash Angles InducedConibinationof Bties With an Unswept_. _. . .Provided by IHSNot for ResaleNo repr
26、oduction or networking permitted without license from IHS-,-,-,12Q.NACA TN 28943. Rogallo, Vernon L.: Effects.of Wing Sweep on the Upwashat“theTropeller Planes of MultienginedAirplanes. NACA TN 25, 1952.94. Spreiter, John R., and Sacks, Alvin H.: The Rolling Up of theTrailing Vortex Sheet and Its Ef
27、fect on the Downwash Behind.Wings.Jour. Aero. Sci., voI_.18, no. 1, Jen. 1951.,.r .-. -.-.- .- - - -.- - -.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-10 NACA TN 2894.a711I(I. . _. . . .Provided by IHSNot for ResaleNo reproduction or networking p
28、ermitted without license from IHS-,-,-u.1.2894/00/8 060, tI ./oisWfi above or beowwing-chord plane,&, SentispQnsIFigure 1.- Vatiafionback horseshoeof upwosVorte% withof u 40 Sewept-vertical posilon.-.- - .-”. - -. -.- -“-_ -, -. -_ . -. - -.Provided by IHSNot for ResaleNo reproduction or networking
29、permitted without license from IHS-,-,-iNACATN 289412.5.4-.3/t r/ 2 3 “. 4i!4Lat8ral posihbn, Fn9 2.- 7W upwash of an Mhite cylinder h o tmn plum.(. - . - .-. . Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-RACA TN 2894 . 13.Fime 3. Mod B mounted i
30、nthek o-by 8&i?oot wtnd tunnel.- . J_ ._ -._. _ _. ,_ _ .- . . -. .Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-14.,NACATN 2894II!.+!I.4G!A91c moc t218fc Q75C+ . . . .0.195C Lwc c OJ95C 0.75C c. .-ModelA ModelBi!Q181ca195c MC175c . -Q75C c m95c. .
31、ModelC.,it10.75CModelDModelEModel AAspect rmio 10Ael/e /ocotion, Inboard 025Oufboad 0.50Toper ratio 0.34Nacelle inclinationNote: Extent offigureModelFB c D E F/0 Z3 Z3 Z3 73025 0.3/ 0.3/ 0.3/ 0.3/0.50 Q62 0.34 0.49 0.49 . Q49 0.490 0 00 00 -70survey from nacelle center hne, 0J9c to 0.61c.4. Semispan
32、 models. A, 400. . . . . . -. -. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA TN 2894s15I Diagonalsam lines II of psrf*cfcvrmhtion. II I I I4 8 /2 /6Meusured upflow angle, A, deg wFigure 5. Comparison of predicted and meusured upflowfor six semispun models of severul ungles of uttuck.NACA-Laey - 2-17-s3 -1000- - - -. .- .- . - -. - - . . . .- - -Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
