REG NACA-TR-571-1937 Pressure distribution over a rectangular airfoil with a partial-span split flap.pdf

1、REPORT No. 571PRESSURE DISTRIBUTION OVER A RECTANGULAR AIRFOIL WITH A PARTL4L-SPANSPLIT FLAPBy CARL J. WDNZINQEIIand THOMASA. HARRISSUMMARYPremuredixh-ibuiien test of a Clark Y wing moddwith a partial-span qiit ji%p were maak to determimthe dtitribdon of air load ouer both the wing and theflap. The

2、model wu wed in conjunction with a re-flection plane in the N. A. C. A. 7- by 10#oot windhum-d. Tlu fiO-percenLchordephl .jizp exiemi.ed overthe inboard 60 percent of the sennkpan. The teek weremao%cd variOIMjlap dejleckionaup to o and covereda range of angleaof aitack+om zero lift to approximdelyma

3、ximum lijtfor eachfip o?gilection.The r. .i . -I i I I I. .;.-yygg -+=: !I,- - - - - . . : .-.-.-.-.-30.=0.60-.P,=IIII7 I .5 4. I I m6;”;5J -I* !+I QJII IFmune a record was then taken of the pressures atthe orifices by means of the photographic manometer.PRESENTATIONOF DATASeotion or rib pressure di

4、agrams with the flap neutral(. 4) are given as ratios of point pressurep to dynamicpressure q for a low angle of attack ( 60), an inter-mediate angle of attack (60), and a high angle ofattack (150). h addition to the section pressurediagrmns with the flap neutral, the increments ofpoint pressure wit

5、h the flap deflected over the pointpressure with the flap neutral (both in terms of thedynamic premure) are given (figs. 6 to 7) for allflap deflections and for the thee previously mentionedangkwof attack. On these diagrams the flap preasureaare plotted from the deflected flap chord but normalto the

6、 wing chord. Tho principal advantage of theincrement diagrams is that they may, by the principleof superposition, be applied to pressure diagrams ofany other basic wing section that does not depart toogreatly from the Clark Y section of which the testswere made.Provided by IHSNot for ResaleNo reprod

7、uction or networking permitted without license from IHS-,-,-PRESSURE DISTRIBUTION OVER A RECTANJL4R AIRFOIL 495The data computed from the integrated pressure Mdiagrams are given 99 nondimensionrd coefficients. cm4=gcu* pitig-moment COdicientThe coefficients for the wing-and-flap combinationabout qua

8、rter-chord point. flap section hinge-moment coefficientincludeJthe loads of the flap projected onto the wing %= *c,:oe from wmgf flap normal-force coefficient.ON,=:(C. F.)z= 0.25 )mmaX100, wing center of pres-%14= , airfoil section pitching-moment .qcu sure in percentage. ofcoefficient about quaxter

9、chord wing chord from wmgpoint. leading edge.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-496 REPORT NO. 571 NATIONAIJ ADVISORY CO FO13 AERONAUTICS()J X100, flap. section center of pre9-(C.p.)f= : f sure m percentage of flapchord from hinge.oh,()

10、c.F.)f= X1OO, flap center of presure in%inercentage of flap chord fro nge.()(c. P.).,a, = * X100, wing-lateralcenter of pes-Ww4 sure in percene of wmgsemispan from wmg root.d, W pitching moment about the quarter-lMchord point.Lf, flap section hinge moment per unit sprmabout the flap hinge.H, flap h

11、inge moment about the flap tinge.% mornt of wing semispan od aboutwmg root.Mkt, moment of flap semispan load about in-board end of flnp.q, dynamic pressure.cm,wing chord.Mfh,()c.)”= X100, flap lateral center of pre9-4 sure in percentage of flasemisDamfrom inboard en:of fla.whereM is the airfoil sect

12、ion normal force per unitspan.NW,wing normal force.nf, flap section normal force per unit span.iVf, flap normal force.% i. e., thelongitudinal center-of-pressure positions and the pitch-ing-moment coefficients were derived solely from con-siderations of the normal forces.The airfoil section normal-f

13、orce coefficient are plot-ted against the wing semispan in figure 8 for allflap deflections and all angles of attack tested. TheProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-PRESSURE DISTRIBUTION OVER A RECTANGULAR -OIL 497airfoil section centers o

14、f pre3sure are plotted similarlyin figure 9. In addition to these data, the incrementsof airfoil section normal-force and pitching-momentcoefficients, Ac and Ac, for the three angles ofattack previously mentioned are given in iigure 10.The airfoil section coefficients C=and % are also plottedagainst

15、 angle of attack for all the flap deflections infigure 11. The wing normal-force and pitching-momentcoefficients and longitudinal centers of pressureare plot-ted against angle of attack for all flap deflections infigure 12, and the wing lateral centers of pressure aregiven for all flap deflectionsin

16、 figure 13.The flap section normal-force coefficients are plottedagainst flap sernispan in figure 14 for all flap deflec-tions and angles of attack. It should be noted thatfor 6,= 0 the coefficients were computed for the loadon only the lower surface of the flap, whereas for theother flap deflection

17、s the coefficients include the loadson both the upper and lower surfaces of the flap. Thiscondition also applies to the flap centers of pressure andhinge-moment coeficiemk. The flap section centers ofpressure for all flap deflections and angles of attackare plotted against flap semispan in figure 15

18、 Theflmp normal-force and hinge-moment coefficients andlongitudinal centem of presmre are plotted againstwing normrd-force coefficients in figure 16 for all flapdeflections, The flap lateral centers of pressure areplotted against angle of attack in figure 17.PRECISIONInasmuch as no air-flow alineme

19、nt tests were madein the wind tunnel with the test arrangement usedfor this investigation, the absolute setting of the angleof attack may be slightly in error; the relative anglesare, however, accurate to within + 0.1. The flapdeflections were set to the speciiied angles to within*o.l”. The point pr

20、essures based on check tasts inwhich both the angle of attack and the flap settingswerechanged independently showed that they agreed towithin +2 percent, with the exception of the upper-surface pressures near the wing leading edge which,at high angles of attack, checked to within +5 percent.The dyna

21、mic pressure recorded on each diagram wasaccurate to within therefore variations of the dynamic pressuredo not introduce any error in computing the coefficients.None of the data has been correctad for the effects ofthe jet boundaries.RESULTS AND DISCUSSJONSECTION PRE9SUR E DISTRIBUTIONThe ,stributio

22、n of pressure over the airfoil sectionswith the flap neutral (fig. 4) is typical of that for wingsof4”Fectanguhm plan form. The expected high tipR npFIQUBE10.Inawmentain airfoil sectionnormal-forceand pltoblng-momentcli-ckmtdwith the tip deSwtd vmicnn amounts.loads at the high angle of attack verify

23、 previous con-clusions that structurally the rectangular tip shape ispoor. The data for angles of attack other than thoseshown were not believed to be of sufficient generalintarest to include in this report.The increments of pressure due to the deflected flapat the low angle of attack, 6, (iig. 5) s

24、how that thepartial-span flap ailects the load distribution on allsections along the span of the wing. The fit sectionoutboard of the tip of the flap, section D, shows aProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-* .- .4- .498 REPORT NO. 571 NATI

25、ONAL ADVISORY CONMTIT!E13 FOR AERONAUTICSo 111111111111111” .-OFFI,I I I I I I I I I I I I I I %. I I ! I I I I ! I ! ! I I I I I I n. I I I.3 I I I I I I I I1 1 I 1 I 1E12 .+#H1 I I I I I.64200-.1Cl-.2:32.0f.8161.4Il+Etl.6.4.2 VAA#$fJI 1 I A/ /-2 ww-.4 Id-16 -12 -8 -4 0 4 8 12 16 +6 -/2 -8 -4 0 4 8

26、 12 16a, deesFmurm11,-Afrfc41don normal-form?and pltcbhe flap is large, increasing with flap deflection. The$-.E$.$:QLQqG$-16 -12 -8 -4 0 4 8 12 16a,degreesWUMI 13.-Lateralmum of prsorO Of wfq wftb the tip deS,;,;=I I I Id, degrees -90-3 o -3” a75 -6 d ,oegrees-15 * v-6”+-(2”- 3?_LA +LL!-g” X-ls”,5,

27、 m I l-l 1-1.C.0.8t-illl llllll-lLlll I I I I* !-LL I -LJ_l-!-14-l- ll_-l-l I 1=L I I I I I I I I I I I I IrtI I I I I 1 I I I I I 1 1 t I 1 ! , , ,I I I I I I I I I I I%of flopsemkpan TipFIGTJBB14.-SW lcd dlshibuUon onflaph varionsS8Pdefkdons.for other flap deflections the flap center opressure is

28、essentially constant between 40 and 50percent of the flap chord from the hinge axis.J I I I I I I I I I IFIQOEE l&Kormal-force me13den& Mngemommt coefOden& and centers OLpramuo of IMP for vmiorn tip delleclfmmd C, degreesQUEE 17.bteId c311kxsOf of tip forvarioustip detktfoxuThe flap hinge-moment and

29、 normal-force coeff-icients (fig. 16) increase with flap deflection but showno consistent variation with wing normal-force coeffi-cient. The maximum flap normal-force coef%cient was1.15, which checks the results of references 2 and 3 forthe same flap deflection. The maximum hinge-momentcoefficient o

30、f the flap was 0.5, which is about 10 percentlessthan thatreported fort.hefull-spanflap of reference.for small values of the wing normal-force coefficientwith the flap down 45. With the flap neutral thecenter of pressure moves to about 65 percent of theflap chord at small values of wing normal-force

31、 coeffi-cient. The lateral center of pressure on the flap (fig,17) is at 50 percent of the flap span from the plane ofsymme, within +0.5 percent, for all flap deflectionsand angles of attack tested.The amount of leakage between the wing and aclosed split flap largely determines the hinge-momentand n

32、ormal-force coefficient for the neutral setting.If there is any negative pressure on the upper surfaceof the flap in the closed position, the hinge-momentand normal-force coefficients wilI be increased. It ispossible that the force required to overcome the hingemoment when the flap is neutral may be

33、 critical formanual operation of the flap. Further teds of variousflap-neutral conditions seem desirable.CONCLUSIONSThe following conclusions may be drawn from theresults of the tests reported herein:1. Deflection of the partial-span split flrLpaffectedthe pressures and section normal-force and pitc

34、hing-moment coefficients over the entire span of the wing.2. For the &g-flap combination tested, the flaploads and moments were practically constant over thespan of the partial-span split flap for a given flapdeflection and angle of attack of the wing.3. The maximum normal-force and hinge-momentcoef

35、ficients were about the same for the partial-spansplit flap of the present tests M for a previously testedfull-span split flap.LANGLEY MEMORIAL AERONAUTICAL LABORATORY,NATIONAL ADVISORY COmTPED FOR AERONAUTICS,LANGLEY FIELD, VA., API-U28,19$6.REFERENCES1. iVeic& Fred E., and Harria, Thomaa A.: The A

36、erodymunioaractdatica of a Model Wing Having a Split FJapDeflected Downward and Moved to the Rear. T. N. No.422, N. A. C. A., 1932.2. Wenzinger, Carl J.: Wind-Tunnel Merumrementa of AirLoada on Split Flaps. T. N. No. 498, N. A. C. A., 1934.3. Wallace, RudoE Invedigation of Full-scale Split Trailing-

37、Edge Wiig FIaps with Various Chordc and Hinge Locn-tiona. T. R. No. 539, N. A. C. A., 1935.!. Wenzinger, Carl J.: The Effect of Partial-Span Split Flapson the Aerodynamic Cbaraobristkc of a Clark Y Wing.T. N. No. 472, N. A. C. A., 1933.5. TVenzinger,Carl J.: The Effects of Full-Span and Partial-Span

38、Split Flapa on the Aerodynamic Characterictioa of aTapered Wing. T. N. No. 605, N. A. C. A., 1924.J. ParaonE,John F.: Full-Scale Force and Preeaurm-DistributionTeA on a Tapered U. S. A. 45 Airfoil. T. N. No. 521,N. A. C. A 1936.The longitu&nsl centar of prwe on the flap (k.7. Hm o A.: me 7 by 10 Foo

39、t Whd Tunnel of the16) is about constant at 43 percent of the flap chord National Advicory Committee for Aeronautics. T. R. NO.from the hinge axis except when the flap is neutral and I 412,N. A. C. A. ,1931.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-