1、/Z130 apoears to be associated withlaminar separation on the top surface and a turbulent reattachment onthe bottom surface. On the top surface the typical subcritical Reynoldsnumber pressure distribution is indicated in figure 13(a) with separationover more than half of the upper surface. On the low
2、er surface the pres-sure shows a pattern similar to that for the supercritical Reynolds num-ber in that the negative pressure coefficient increases behind the flap.Evidently, the turbulent flow from the flap reattaches to the cylinderand the turbulent boundary layer allows the lower surface separati
3、on pointto occur farther back on the cylinder. The asymmetry of the resultingflow produces the negative lift force.The two flaps 180 apart (see fig. 7) _ay also be considered as adrag-producing device in which case the cylinder fitted with flaps(c/d = 0.00) has nearly as high a maximum drag coeffici
4、ent at a Reynoldsnumber of 520,000 as a flat plate normal to the airstream. At 6 = 90othe flaps with separated flow behind gave a drag coefficient of 1.8 whichis close to the value of 1.98 quoted in reference 5 for a two-dimensionalflat plate. The value of cd = 1.8 represents a sixfold increase in t
5、hedrag coefficient when compared with that of the plain cylinder at aReynolds number of 520,000. (See fig. 3.)L936SUMMARY OF R_ULTA low-speed investigation has been mad_ on a two-dimensional liftingcircular cylinder over a Reynolds number range from 135,000 to 1,580,000to determine the force and pre
6、ssure distribution characteristics. Theresults are summarized as follows:i. The critical Reynolds number for th_ lifting cylinder with ao-percent flap deflected 90o was approximately 350,000.2. i_nelift coefficient which showed a wide variation with Reynoldsnmllber varied from a low of about 0.2 at
7、a Iieynolds number of 165_000 toa high of 1.54 :_t a Reynolds number of 350_(_00 and then decreased almostlinearly to a w_lue of 1.0 at a Reynolds nu_iber of 1,580,000 for the 6-percent flap deflected -20.3. The drag coefficient of the 6-percelt flap configuration variedlinearly from a minimum of 0.
8、o at a Reynold_ number of 350,000 to a maxi-mum of 0.9 at a Reynolds number of 1,580,000.4. The lift-drag ratio for a 0-percent flap deflected 90 varied froma low of 0.15 at subcritical Reynolds numbers to a maximum of 2.54 at theProvided by IHSNot for ResaleNo reproduction or networking permitted w
9、ithout license from IHS-,-,-2Zbeginning of the supercritical range. It then decreased with increasingReynolds number.5. The pressure distributions for the 6-percent flap configurationshowed that the loss of lift with Reynolds number was the result of theseparation point moving forward on the upper s
10、urface. Pressure distribu-tions over a plain cylinder also showed similar trends with respect tothe separation point.6. Tests of a 0.37-percent flap gave a lift coefficient of 0.85 ata Reynolds number of 520,000 with the same lift-drag ratio as the largerflap but the position of the flap for maximum
11、 lift was considerablyfarther forward than on the larger flap.7. Tests of two 6-percent flaps spaced 180 apart showed a changein the sign of the lift developed for positions of the flap greater than132 at subcritical Reynolds number. The drag coefficient developed bythe flaps when normal to the rela
12、tive airstream was approximately equalto that developed by a flat plate in a similar attitude.Langley Research Center,National Aeronautics and Space Administration,Langley Field, Va., June I, 19GO.REFERENCESi. Lockwood, Vernard E., and McKinney, Linwood W.: Lift and Drag Char-acteristics at Subsonic
13、 Speeds and at a Mach Number of 1.9 of aLifting Circular Cylinder With a Fineness Ratio of i0. NASATN D-170, 1959.2. Bursnall, William J., and Loftin, Laurence K., Jr.: ExperimentalInvestigation of the Pressure Distribution About a Yawed CircularCylinder in the Critical Reynolds Number Range. NACA T
14、N 2463, 1951.3. Schlichting, H.: Lecture Series “Boundary Layer Theory“ - Part II -Turbulent Flows. NACA TM 1218, 1949.4. Polhamus, Edward C., and Spreemann, Kenneth P.: Effect of High Sub-sonic Speeds of Fuselage Forebody Strakes on the Static Stabilityand Vertical-Tail-Load Characteristics of a Co
15、mplete Model Havinga Delta Wing. NACA RM L57KI5a, 1958.5. Hoerner, Sighard F.: Aerodynamic Drag. Publ. by the author(148 Busteed, Midland Park, N.J.), 1951.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-10_44Flop - -_-It; _IiCylinderEnd plateMode/ i
16、n 7 - by I0- foot tunnel_- Tunnel wallIo_Lift_- _ / _-FlopWind _ -_- i -JC/d=O.06_3c=.500._ _L -i-_.50 7- - -=Jc=.500._L_.37- percent flap6 - perce n t flopF_ps /80 apartFlop configurationsFigure i.- Diagram of model and flaps used in the investigation. (Alldimensions are in inches.)Provided by IHSN
17、ot for ResaleNo reproduction or networking permitted without license from IHS-,-,-ii2.0x_oIlOR.8.4.200 .05 .lO .15 20 25 .30 35MFigure 2.- Variation of Reynolds number with Mach number for theinvestigation.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-
18、,-,-12Czc+oE+=“Pt_16 ._tE+4:+I.+!_: : +.t_b:tt:4 r,._.o !i2o_ -+!tP,ttti,+B = 90Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-z3Do_Iq_,/jrFiI/i ./.t.ir/;t iJ“ / L - _“tt _t-q“_,-_ _ _ _ ro _k _ _ J _ _ Ih_%_qq_o_1p-Hh0J-p0.r-i-p,.aq_,d_ohO_C_00_-_
19、.,-.tH HH0 _HH0I1)04-_!Ai1)-r-tProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-_4J“t !iil_1!.ti:_ _:, !lit:44 4:1Cd i! ;:I; :.:i:,_ifl,tH ;r!:t_. ,_ t!:t:!:1iii _iili !i;?_! ,h_;i_a:,!i :i! II!N “_i_ :ii;It:l0 :_: _ _ i!ti!i :i?t:l_, ,4+,1 ,*tlFI+I,.
20、,+ +,.,_,., ,tt-_:ti :i ,:i :i_,_:, , ,_,;:; + ,.77-7t7:-_ ._,;T;: ,*:_:H, _/61:_.ii! .:_:_ ,_, -:_ri,“ ,-,t ,.;, :+i, ,:;I;: :!i:i: ),“ i :_4 i:it+l: r ;z.t :L_ : ,oiii!i_:ii iLii_i !i_!ii_iitt-tt,t_:;_ :4:;: -!_!iiff_:i:i:i !:!ii!i ii:!:!i30Z! I_t.*t“!i:40 50 60Figure 5.- Effect of flap angular po
21、sition cn the aerodynamic character-istics of a lifting cylinder for two Reynolds numbers, c/d = 0.06.IOProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-15,.oI;ll:ii: /2,4+,_ +4+.+_.-ot,!t,*r!.Ti_;i:;!t:I_:tii,!i,l_,lii!:t!_:iI,DFigure 7- Effect of fl
22、ap angular position on the aerodynamic character-istics of a cylinder having two flaps 180 apart, c/d = 0.06.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-3Z17_oo_I0 50 t00 150Figure 8.- Effect of Reynolds number on the pressure distribution abouta
23、 lifting cylinder, c/d = 0.06; 8 = 90 .Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-i8,:i _: liib - _ + I i _ Lower surfoce iio_- _ , t: i! I I + . _ i R=601,O00Cp/0G-IIt,Ok.iFigure 8.- Concluded.Provided by IHSNot for ResaleNo reproduction or net
24、working permitted without license from IHS-,-,-!- T_ _ Lower surface _-o Upper surfaceR=502000 R = 1,005,000q:)I0Figure 9.- Effect of Reynolds number on the pressure distribution abouta plain cylinder.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-2
25、OI!xDO_(a) R = 520,000.Figure i0.- Effect of flap angular position o_the pressure distributionabout a lifting cylinder. Tick refers to flap position, c/d = 0.06.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-21Dc_I_/I “Li_#=60 I:ii!0 50 /0“0 GO_,deg
26、= I00 o(b)i IIT “IR = i_216,000.G =/20 Figure i0.- Concluded.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-22!,DG“50 /_8=90 cp: J150 0 I50(a) R : 520,000.Figure ii.- Effect of flap angular position on the pressure distributionabout a lifting cylind
27、er. Ticks indicate flap position, c/d : 0.0037.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-23_DI0 50 I00 /.50O, d_/0 I5O t00 150(b) R = 1,216,000.Figure ii.- Concluded.Provided by IHSNot for ResaleNo reproduction or networking permitted without l
28、icense from IHS-,-,-249o3o2Oi0gIII103O6O 7o 80 9o ioo 11o 12o17otI_4C9o 60 70 8O 9O zoo no 12oFigure 12.- Effect of flap height on the pressure distribution about acircular cylinder. 5 = 90o; R = 520,000.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-
29、,-4Z25OO_II0/-2i8=1400(a) R : 190,000.Figure 13.- Effect of flap angular position on the pressure distributionabout a cylinder having two flaps 180 apart. Ticks indicate flapposition on respective surfaces, c/d = 0.06.Provided by IHSNot for ResaleNo reproduction or networking permitted without licen
30、se from IHS-,-,-26!koRNOxf10(b) R = 520,000.Figure 13.- Contirued.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-27Lower surfoceUpper surfoceLii0Cp_/Z =120 /50 0 50d;,de g(c) R : 1,038,000.Figure 13.- Concluded.NASA- Laagley Field, Va. L=936Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
