NASA NACA-TN-4200-1958 Effectiveness of boundary-layer control obtained by blowing over a plain rear flap in combination with a forward slotted flap in deflecting a slipstream down.pdf

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1、-a0=a-NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS-1m(3=.-TECHNICAL NOTE 4200EFFECTIVENESS OF BOUNDARY-LAYER CONTROL, OBTAINED BYBLOWING OVER A PIJUN REAR FLAP IN COMBINATION VLlI133A FORWARD SLOTTED FLAP, IN DEFLECTING A SLIPSTREAMDOWNWARD FOR VERTICAL TAKE-OFFBy Kenneth P. SpreemannLangley Aeronaut

2、ical LaboratoryLangley Field, Va.WashingtonFebruary 1958Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TECH LIBRARYKAFB,NMz.w.NATIONAL ADVISORY COMMITTEE FORETFESTIVENESSBIQWG OVERTECHNICAL NOTEOF B3UNDARY-LAYERAPIAINRFARFIAP4200AERONAUTICS llllllll

3、liullllllllilllll0ilbLi325CONTROL, OBIAINEDBYIN COMBINATION WITHA FORWARD SIOTIEDFIAP, IN DEFLECTING A SHPSTRFAMlXWNWARD FOR VERTICJILTAKE-OFF Kenneth P. SpreemannSUlMRYAn investigationof the effectiveness of boundary-layer control,obtainedby blowing a Jet sheet of dr over a plain rear flap in com-b

4、ination with a forward slotted flap, in deflecting a propeller slip-stream downward for vertical take-off has been conducted in a static-thrust facility at the Zangley Aeronautical laboratory. The investigationindicated that the plain rear flap alone with a low momentum coefficientfor boundary-layer

5、 control provided larger turning angles than the com-bined slotted and plain flaps without boundary-layer control. Withinthe region of ground effects the configuration of this investigation mani-fested reductions in turning angle and ratio of resultant force to thrustthat were similsr to those shown

6、 for numerous configurations of previousinvestigationswith or without boundary-layer control.The slotted and plain flap of this investigation (withboundq-layer control over the rea flap) provided larger turning angles andratios of resultant force to thrust than the double plain flap config-uration o

7、f a previous investigation (withboundary-layer control overthe forward flap).INTRODUCTIONAn investigationof various wing-flap configurations has been con-ducted at the Langley Laboratory in an effort to develop simple arrange-ments capable of deflecting the propeller slipstream downward for vertical

8、take-off. The capabilities of some of these configurations are reportedin r-erences 1 to 6. The effect of blowing boundary-layer control on theability of a ting to deflect the slipstreamwas investigated in refer-ences 5 and 6. In these studies boundsry-layer control was applied at9wProvided by IHSNo

9、t for ResaleNo reproduction or networking permitted without license from IHS-,-,-2 NACA TN 42OOthe knee of the first flap. Experience haa shown, however, that flowseparation is most likely to occur on the second flap. Therefore, anexploratory investigationwas undertaken to determine the slipstreamde

10、flection characteristicsof a wing with blowing boundsry-layer controlapplied only to the second flap. The investigationwas conducted in astatic-thrustfacility and employed a model wing equippedwith a67-percent-chordslotted forward flap and a 33-percent-chordplain rearflap. A full-span blowing nozzle

11、 was located at thethe forward flap for applying boundary-layer controlcoEFFIc!ms m SYMKKsThe positive sense of forces,is indicated in figure 1. bentsof the mean aerodynamic chord.b/2cDhbf,lf,2LFxMFTe%“trailing edge ofto the rear flap.moments, and angles used in this paperare referred to the quarter

12、-chordpointwing semispsn, ftWi chord, ftpropeller diameter, ftheight of wing trailing edge above ground, ftdeflection of forward or slotteddegdeflection of rear or plain flapchord, deglift, lblongitudinal force (thrustminuspitching moment, ft-lbresultant force, lbpropeller thrust, 15 lbturning angle

13、, inclination ofthrust axis, tan- L degq%vnmoment coefficient, q“sflap relative to wing chord,relatim to slotted-flapdrag), lbresultant-forcevector fromw.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA TN 42c0A qllu %“Ps.Qnf%VnP“,!“sPP“tflow coe

14、fficient, %Epressure coefficient, p - “q“()3Pn+gvnpower in blowing system, ft-lb/sec2power in slipstream,quantity of air blownstatic pressure, cuP“ #D2(V”)34ft-lb/sec4out of nozzle expandedftsecmass density of air blown out ofnozzle exit velocity, isentropicstatic pressure being assumed,to slipstrea

15、mnozzle, slugs/cu ftexpansion to slipstreamftfsecmass density of air in slipstream, slugs/cu ftslipstreamvelocity, ft/secTslipstreamdynamic pressure, lb/sq ft7iD2/4wing area of semi.spanmcdel, sq ftstatic pressure in blowing system, lb/sq ftslipstream static pressure, lb/sq fteffective nozzle gap, i

16、n.APPARATUS AND METHODA drawing of the model, with pertinent dimensions, is presend infigure 2, and a photograph of the model mounted for testing is shown infigure 3. The geometric characteristicsof the model are given in thefollowing table: -Provided by IHSNot for ResaleNo reproduction or networkin

17、g permitted without license from IHS-,-,-4 NACA TN 4200Wing:Area (semispan),sq ft . . . . . . . . . . . . . . . 3.0Span (semlspsm)ft. . . . . . . . . . . . . . . . 2.0Chord, ft . . . . . . . . . . . . . . . . . . . . . . . . . 1.5Aspect ratio. . . . . . . . . . . . . . . . . . . . . . . . 2.67Taper

18、ratio . . . . . . . . . . . . . . . . . . . . . . . . 1.0Airfoil section (approximate) . . . . . . . . . . . . . . NACA 4412Propeller:Diameter, ft. . . . . . . . . . . . . . . . . . . . . . . . 2*ONacell.ediameter, ft. . . . . . . . . . . . . . . . . . . . 0.33Airfoil section . . . . . . . . . . . .

19、 . . . . . . . . . . ClarkYsolidity. . . . . . . . . . . . . . . . . . . . . . . . . . 0.07The model was made up by using the wing which was employed in refer-ence 6 as the flap of the present model. A new leading-edge sectionwasadded to increase the total chord to 18 inches. This combinationresulte

20、din a 12-percent-thickairfoil section.The profile of the forward slotted flap approximated that of theslotted flap 2-h of reference 7. The leading psrt of the wing and theslotted flap were attached together by externalbrackets as shown infigure 3. With the slotted flap deflected, the gap between the

21、 trailingedge of the fixed pert of the wing and the nearest point on the leadingedge of the flap was held cotant at 0.014c for all flap angles. (Seefig. 2.) The plain rear flap was hinged at 67 percent of the wing chord.The slotted flap contained the plenum chaniberand blowlng nozzle.The plenum chsm

22、ber extended through the wing root terminated in aplate which served as a base for mounting the model on the balance. Adrwas exhausted through the nozzle over the plain rear flap. (See fig. 2.)The fuX1-span nozzle, employed for boundary-layer control, had an effec-tive nozzle gap of 0.017 inch.The f

23、low coefficient,pressure coefficient,and ratio of power inblowing system to power in the sl.ipstresmare plotted against momentumcoefficient in figure 4. The mass flow through the nozzle was measuredby means of a standard sharp-edge-orificeflowmeter. Air was suppliedthrough a l/2-inch line at 90 poun

24、ds per square inch.For these tests the propellerwas mounted independentlyas shown infigures 2 and 3. The propeller was driven by a vsxiable-frequencyelec-tric motor at about , revolutionsper minute, which gave a tip Machnumber of approximately0.52. The motor was mounted inside sm aluminum-all.oynace

25、lle by means of strain-gagebesms in such a way that the pro-peller thrust and torque could be measured. The total lift, longitudinalforce, and pitching moment of the model were measured on a strain-gagebalance located at the root of the wing.wProvided by IHSNot for ResaleNo reproduction or networkin

26、g permitted without license from IHS-,-,-NACA TN 42NJ 5. !I!heground was simulatedby a sheet of plywood as shown in figure 1.The ground board extended about 2 feet in front, 3 feet behind, and2 feet beyond the wing tip of the model. All tests with the ground boarda71 were conductedwith an angle of 2

27、0 between the ground board and thrustaxis of the propeller.The investigationwas conducted in a static-thrustfacility at theLangley Aeronautical Laboratory. All data presented were obtained atzero forward velocity with a thrust of 15 pounds frcm the propeller.Inasmuch as these tests were conducted un

28、der static conditions in a largeroom, none of the corrections that are normally applicable to wind-tunneltests were employed.RESULTS AND DISCUSSIONThe results of the static tests of this investigation to determinethe pitching moments, ratio of resultant force to thrust, turning angles,and power requ

29、ired in the blowing system for vsrious flap deflections arepresented in figures to 8 for configurationsaway from the ground.Figures 9 to 12 show results for cotiigurationswithin the region ofground effects. The effects of the combined flaps and the plain rearflap alone on the turning sngle, ratio of

30、 resultant force to thrust,md ditig moments for different momentum coefficients sre summarizedin figure 13. The values of F/T and e presented in figure 13 wereobtained from figures to 8 by selecting the largest vslue of F/T ata specific turning singlefor the particular value of “ desired. Infigure 1

31、4 the envelopes of the vsriation of F/T with e and the divingmoments for the model of this investigationare comparedwith those forthe plain-flappedmcdel (withblowing over the forward flap) of refer-ence 6. A representativeplot of the effects of height above groundon 0 and F/T for the mcdel with bf,l

32、 = 40 and 5f,2 = 40 obtainedfrom figure 10 is shown in figure 15. The variationwith height aboveground of the pitching moment, ratio of resultant force to thrust, andmomentum coefficientrequired to maintain a constsmt turning angle of“, takenfromfigure 11, is shown in figure 16.The momentum coeffici

33、ents in this investigationsre based on thecalculatedmass flow rather then on the mass flow determined from themeasured thrust. For this configuration the measured thrust was 20 to25 percent lower thsn the calculated thrust indicatidby the flowmeter.These losses may be attributed in part to skin fric

34、tion over the flapas well as to losses in the nozzle.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-6 NACA TNEffects of Flap Deflection and Ecmndary-kyer ControlThe mmma.ry data of figure 13(a), giting the envelopes of thetion of F/T with (3,show th

35、at below the stall the increases in4200varia-F/Tfor the m the calculatedvalue of AF/T = CV”these increases in diving moments can be associatedwith the increasesin B, F/T, and movement of the flap system rearwardwhen the forward flap is deflected.From the comparisonin figure 14 it is seen that the sl

36、otted snd wplain flaps of this investigationwith blowing over the rear flap providedlarger turning angles and ratios of resultant force to thrust than thedouble plain flap confQuration of reference 6 with blowing over the for- mward flap. The relative merit of boundary-layercontrol on the first orse

37、cond flap segment is difficult to determine from the comparisonplotof figure 14 since the double-slotted-flaprangement had considerablylarger values of 13 and F/T for the zero Cp” case. The incrementsof F/T and 13 producedby boundary-lsyer control in the two casesappear to be generally about equal.E

38、ffects of oximity to GroundPreviouswork (refs. 3 to 5) has indicated that the reductions inF/T and 0 near the ground for a deflected slipstreamwere partiallydue to rear flap separation. It was, therefore,hoped that, by theapplication of boundary-layercontrol to the rear flap, this separationcould be

39、 suppressedand these undesirable ground effects reeved. Thedata of figures 9 to 12 and the summsry data of turning effectivenessinfigure 15 indicate that this condition cannotbe realizedwith a fixedpllsetting. Boundary-layercontrol prtided overalll.increases inturning effectivenesswithin and out of

40、the region of ground effects.Within the region of ground effects,however, the action of the Jet sheetimpinging on the ground apparently causes more of the slipstreamto passover the top of the wing and results in a loss in 0 and F/T nesr theground. (See fig. 15.) This action has been folly discussed

41、in refer-ence 3.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA TN 4200 7A study of figures 9 to 12 indicates that by suitable scheduling of.Cp” the effeet of the ground on 8 csn be eHminated and F/T can beincreased as the ground is approached.

42、Figure 16 illustrates how CA”dwould have to be scheduled in order to maintain a constant turning angleof yo . There is the possibility, however, that the power required forsuch a systernmight be relatively large very near the ground for someairplane applications. For exsmple, in figure 16 it is seen

43、 that aC “ of 0.09 in order tovalue of h/D of 0.1 requires a value of maintain a constant turning angle. The dataof figure 4 indicate that,in order to provide a value of Cp” of 0.09, a ratio of power in theblowing system to power in the slipstream of about 0.30 is required.CONCLUSIONSAn investigatio

44、nof the effectiveness of boundary-layer control,obtainedby blowing a jet sheet of air over a plain rear flap in ccmibi-nation with a forward slotted flap, in deflecting a propeller slipstreamdownward for vertical take-off indicated the following conclusions:1. The plain resr flap alone with a law mo

45、mentum coefficient forboundary-layer control provided larger turning angles than the combinedslotted and plain flap without boundary-lsyer control.2. The configurationof this investigationmanifested about thesame critical rsnge near the ground as was shown for numerous configura-tions of other inves

46、tigationswith or without boundary-layer control.3. The slotted andplainflaps of this investigation (withboundary-layer control over the rear flap) provided larger turning angles andratios of resultsnt force to thrust than the double plain flap configura-tion of a previous investigation (withboundary

47、-layer control over theforward flap).Iangley Aeronautical Laboratory,National Advisory Comittee for Aeronautics,Langley JH.eld,Vs., November 12, 1957.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA TN 4200REFERENCES1. Kuhn, Richard E., and Drape

48、r, John W.: An I.nvesti.gationof a Wing-Propeller ConfigurationEnploying Large-ChordPlain Flaps Large-Diameter Propellers for Low-SpeedFlight and Vertical Take-Off.NACA TN 3307, 1954.2. Kuhn, Richard E., and Draper, JohnW.: Investigationof Effectivenessof Iarge-ChordSlottedFlaps in DeflectingPropell

49、er SlipstreamsDownward for Vertical Talu+Off and Iaw-speedFlight. NACATN 3364,1955.3. Kuhn, RichardE.: Investigationof the Effects of Ground proximityand Propeller Position on the Effectivenessof a Wing With Lsrge-Chord Slotted Flaps in Redirecting Propeller Slipstreams Downwardfor Vertical Take-Off.