1、SECURITY INFORMATION,.1= . _ =. -L. .- -,. .,- - ., -; WA. -u . .=-a.,L.RESEARCH MEMORANDUMAERODYNAMICS OF SLENDER BODIES AT h consequently,the preceding conclu-sions were based on the bottom profile. This disturbance as well asthat to be mentioned subsequentlyfor angle of attack is attributed to %i
2、rregularitiesin the tunnel flow. Wcauae correctionsof these non- g-unifoties would require considerablymore calibrationdata than arenow aveilable,no attempt was made to evaluate the effect herein. Thedisturbance affecting the side-pressuredistribution at zero angle ofattack was evaluated in terms of
3、 over-all drag and at most gave merror of approximately1 percent. -Angle of attack. - The axial pressure distributions along the topand bottom of the model are presented in figure 5 for three angles ofattack and three Reynolds numbers. The pressure-coefficientticrementsdue to angle of attack, aspare
4、d in figure 6 with theOn the bottom surfaceexperiment snd theory haveprogressively worse as thedetermined from figures 4 and 5, are com-slender-bodytheory of reference 1.of the model (figs. 6(a), 6(b, and 6(c),similartrends, but the agreementbecomes hangle of attack increases. (The humps in.the curv
5、es are attributedto the tunnel disturbancementioned pre-viously.) The effect of Reynolds number upon the agreementwas neg- ligible at 3 angle of attack. At the higher emgles”of attack, nodefinite Reynolds number effect ws.aobservable.On the top surface of the model (figs. 6(d), 6(e), and 6(f), theef
6、fect of increasingthe angle of attack w.to decrease the pressureson the nose section in a manner similar to that predicted by theory.The theoretical curves for a = 3, 8, and 10o cross each other,whereas the experimental curves do not. The differencebetween experi-ment and theory for the cylindrical.
7、portion of the model increased asthe angle of attack increased. This result is attributedto cross-flowseparationwhich will be discussed later.Some improvement in the agreementbetween experiment and theorywith .creasingReynolds number was observed on the forward part ofthe nose; however, the change i
8、n the agreement for the rest of the bodywas negligible.Experimentalpressure distributionsas a function of the meridianangle around the body are given in figure 7ufor three axial stationsand three Reynolds numbers. Since no conclusiveReynolds number effectwas obtained, only the experimentalpressure i
9、ncrements due to angle.9,.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-2.-.NACA RM E51E13 9of attack for a Reynolds number of 15X1.06are compared with theory infigure 8. Agreement between eeriment and theory is good for CL= 3but poor for a = 8.Bas
10、e PressuresThe variation of base-pressure coefficientwith Reynolds nuniberispresented in figure 9. In figure 9(a) the measured coefficients atzero angle of attack ere compared with the coefficients predicted by themethod of reference 8. The method of reference 8 predicts the correcttrend, but undere
11、stimates the meaeured values by more than 10 percent.However, in terms of over-all drag this discrepancy amounts to only5 percent.The variation of base-pressure coefficientwith free-stresm Rey-nolds nuniberfor 0, 3, 6, 8, and 10 es of attack is presentedin figure 9(b). For zero angle of attack, the
12、base-pressure coefficientdecreases with increasingReynolds number until a Reynolds numiberof6XL06 is reached and then remains relatively constant. With increasingsingleof attack, the Reynolds nuniberat which the pressure becomes con-stant increases to approximately 12X106 for u = 8.Figure 10 shows t
13、he variation of the base-pressure coefficient withe of attack for five Reynolds nunibers. The base-pressure coeffi-cients for the highest Reynolds numbers decrease as the angle of attackincreases;however, for the two low Relds numbers, the pressure coef-ficient first increases to a maximum near u =
14、3 and then decreasesfor higher anglesof attack. The broken line between the m = Go datais used,to indicate that the true variation of the pressure coefficientin this region is unlmown. This behavior for the low Reynolds numbersmay be associatedwith the movement of the boundery-layer-transitionregio
15、n with increasing angle of attack which will be discussed morefully later. The cross-over of the curves presented in figure 9(b mayalso be attributed to the movement of the boundary-layer-transitionregion with angle of attack.Boundary Layer and Cross-Flow Sep=ationSkin friction. - In order ta comple
16、te the investigation of the com-pon=t drag forces which meke up the tital drag of the body at a . 0,friction-drag coefficientswere obtdned from the experimentally deter-mined displacement and momentum thicknesses for Reynolds numbers ofL406, 806, end 1406. The experimentalmean friction-drsg coeffi-c
17、ients CD for different axial stations are presented in figure s for the pr botcimsurface “, 00.20#m Nominal angle .16 . c d attack r(d%Q o : 8365 .12- 10 o Linearized poten-$ cl tial theory* u. mon / 5CJ o 0 /$LJm- vjncw Q *: .04 Q . AU Pw; -njo nz .16(b) Reyn.lda number R., 8XI.06Sb.ttgi_eurfac: 8,
18、 0 _.c.12.08 n5LA c a UL -f-J.04 n n na nQn u n . c 00 00An no .2 .4 .6 Axial.%tetiOn, li! ft -1.2 1X u1.6 1.8(c) Reynolds number Re, ISXI.06;bottan surface 6, 0.FlgWe 6. - Experimental and theoreticalezie.1variation of pm%=we -coefflciantincrement dueto angle of attcck.-.-$!co.-a71.3,.Provided by I
19、HSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-l?ACARM E51H13 27mcoNINI.041080 + . 3A AA/A “/ *,-.04 v V top surfaoe e, IsoO.10/ 63AAA ID4 O FNominalcngle y Orattcckvv (d:g)+:/D 10 Linecrlzed poten-tial theory(e) Reynolds ntnuber E., 6x106; top smface e, 180.04l
20、/ .90 / . 3 5 9( % w 3 v Vv .A G4. v v-.04 /v ./ T-.060 .2 .4 .6 .6 1.0 1.2 1.4 - 1.6 1.8hial station, x, ft(f) Reync.ldcnwnber Re, 15xI06; top surface 6, 160Figure 6. - Concluded. Experimental cnd theoretical .cxialvarlatlon of pressme-coefficientincrement due to angle of attack.Provided by IHSNo
21、t for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACAW E51H13.,14.12.10.03,C6.04.02002CJ (a)hlal station x, 4 hches; Reynoldn mnnber %, 2X106,.06r.04.020-.02t-.C4 1 I I I I I I II I I I I(b)kid. staticm x, 14 Indies;Reynoldsnumber Re, 2xlC.04.020-.02 J7%I I “ ysyC4lbo
22、 ,6 0 -.5 -1.0C9e .9L I I I I I Io 30 60 90 120 1.30MO .i.lexidlanIMIS1O,8, deg(o)Axial Etitim x, 20.5 InoheajReynolAsnwnher Re, 2xI.06.1!w+_.IFQWe 7. - Rxgerhnentalvariaticm of presmnw meffioient with meridian an.8for given axialstation.Provided by IHSNot for ResaleNo reproduction or networking per
23、mitted without license from IHS-,-,-NACA I/M E5ZEL3 29.mco(NN.14.12.10 ,.OaU%. ,_le of attaok CM(d:g).04 tm o: 5v 10.02 cY-o 1002- ) 7-An /8 (d)Jxial ,tatlat X, 4 tiahes;EeYMlds *- Eu, .CE-iE!:IReynoldsnumker Ib, ReyncIldEnumlwr Re, .9x10S.Pire 7. - tinued. bprimntal. tiatlon of premuxa oc-sfYioientwithmeridiananglefor van axialrtaticn.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
