1、REPORT 1281FLIGHT DETERMINATION OF DRAG OF NORMAL-SHOCK NOSE INLETS WITH VARIOUSCOWLING PROl?HJIS AT MACH NUIWBERS FROM 0.9TO 1.51By R. L SEARS,C. F. MERLE-T,and L. W. PUTLANDSUMMARYFree-jtight te pmv.drag, lbaccehxation of gravity, 32.2 ft/secfMach numberratio of mass flow of air through the duct t
2、o massflow of air through a free-tieam tube of area equalto inlet areastatic pressure, lb/sq ft .total pressure, lb/sq ftpitot stagnation pressure, lb/sq ftReynolds number, based on 7.00-inch body diameterradius, in.time, secvelocity, fpsweight of the model, lblongitudinal distance, measured from th
3、e masimum-diameter station, positive downstream, in.ratio of specific heats, 1.40 for airair density, slugs/cu fttight-path angle, degSubscripts:free strefun1 first minimum-area statione exitd externalF . frontali inlet, at lip leading edgeint internalt totalI SLW?IWAYr%mntlydechwltledNAOA ResearohM
4、emorandmnL each modelhad a dMerent flow rate. The only difference in the ex-ternal geometry of. the three models for each cowling shapewas a slight difference in length, the afterbody being cut offat the station required to g%e the desired exit area.Five of the cowlings were of fineness ratio 3 and
5、had aninlet area 24 percent of the body frontal area. The sixthcowling was of iineness ratio 2.5 and had an inlet area 16percent of the body frontal area. T-ivo related nonductedbodies of revolution were tested-one for each cowling 6ne-ness ratio investigated.The general arrangement of the three mod
6、el configurationstested for a typical cowling of tinenee.s ratio 3.0 and therelated nonducted body is shown in figure 1. Similar infor-mation is presented in figure 2 for the cowling models offineness ratio 2.5. All models had identical b and after-body lines.The afterbody, deiined by a parabolic ar
7、c with its vertexat the maximum- the contourin the region of the lips was identical with that of the para-bolic coding II. Cowling V had blunt lips with an externallip angle of 90. The contour in the region of the lips wasidentical with that of cowling I of the NACA l-series.Cowling VI had the NACA
8、140250 profile.The external profiles in the region of the lips of the fivecowlings of fineness ratio 3.0 are better compared in fgure 4.,+-2” * 3:1,7.(3Q 2B71 INcndwted modsl A542LCOntiguratbn I35.81 ,0 _ - 1Zw 3.21- - _ _-l-Ccrdigvotkm 2- _ -_-2.87-rGlrlfigwtkxl 3 k!ax.dlam. stationFIGURE l.General
9、 arrangement of ducted models with cowlings offineness ratio 3.0 and related nonducted model. All dimeneious nrein inches.t- 40.4 i“”:! ,t232“TNonducted mcdel B 1- this fact largely accounts for the differentmasimurn Mach numbers to which data were obtained for thevarious models. The range of variat
10、ion of Reynolds numberwith Mach number is shown in figure 6 for the models tested.AU models were flown on a zero-lift trajectory and the datapresented are for an angle of attack of OO.-, z.-. -,1 /=!,I %Cowling I: NACA l+PiK300 L7241O.1 _ ._. 1Cowling II: parabolio L71587.1-.- . . . -.-r.coding III:
11、 conic, Sharp lip L-73586.1(a) General views of ducted models.I?munn 5.Photographs of models.Cavfing IV: Conic, beveled lip L-73636.1.- - Cowling V: Conic, blunt lip L-75517.1Cowling VI: NACA 1-40-250 L-75361.1(a) Concluded.FIQURE5.Continued.:,*”.II L. -(b) Nonducted model A on the lnunohor. L-73803
12、.1Fmunn 6.Conc1uded.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-DRAG OF NORMAL+ HOCK NOSE ll?IJETS WITH VARIOUS COG PROFHJES 693TABLE ILPHYSIC configuration 3.(b) Cowling VI: NACA 1-40-260; configurationFIGURE8.Variation of pressure coefficient w
13、ith Maohseveral afterbody stationa for two ducted models. Allare in inches1.4 153.numbm atdimwsionathe incremental surface area of the longer afterbocly isestimated to be 0.002. by erences in CD,CZ1 I.WHdby varying the length of the afterbody, therefore, are believedto be sma and well within the acc
14、uracy of (?D,ezoBASIC DATAThe curves of external drag for each ductecl model nropresented in figure 9. The mass-flow ratio associated witheach drag curve is also given. For conthat is, no air was spilled. An increasing amount of oir wasspilled with configurations 2 and 3. The inlebcontractionratios
15、of configurations 2 and 3 were too great to permit tlminlets to start in the test lMach number range.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-DRAG OF NORMAL+ HOCK NOSE S WITH VARIOUS COWLING PROFILES.3IConfigumticmI I I 1u 1 I IMm(a) Ckxrling
16、I: NACA 1-49-300.I?mmm 9.Variation of estemal drag coefficient and mass-flow ratio with Mauh number for the modelswith varioue cowling shapes.II43587 G-G715Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-REPORT 1281NATIONAL ADVISORY COMMITTWE FOR AER
17、ONAUTICSConfiguratbn3I I C-onfiguroth12(b).9 I .0 1.1 1.2 1.3 I3Mm(b) Chding : p-bdiC.I?mum 9.-Contiiued.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-,.3I.2$-.10I.0.8.6.-. .iConfigurationI2 .(o) CowlingIII: conic, sharp lip.l the sharp-Iip conic c
18、owling has the least drag and the NTACA l-seriescowling has the greatest drag. Comparison of the drag oftho three conic cowling models at M= 1.2 indicates that,for these cowlings of constamt fineness ratio, beveling orblunting the lip caused n small increase in drag over that ofthe sharp-lip conic c
19、owling. It should be noted, however,thnt, of the two conic cowlings which were identical exceptfor lip shape (cowlings IV and V), the blunt-lip conic cowl-ing had slightly lower drag than the beveled-lip conic cowling.Thus, it nppears that the effect of lip bluntness on drag iscritically dependent o
20、n the manner of blunting the lip.Because the ATACA l-series coding and the blunt-lip coniccowling had the same external lines in the region of theinlet lip, it is apparent that the higher drag of the NACAl-series cowling is associated with its greater fullness fartherrermwwd.Tho drag of the pointed
21、nonducted body is greater thanthe external drag of all the inlet models in the transonicrange and at AZ. 1.2 is about equal to that of the cowl-ing which was defined by the same parabolic arc. At all testhlach numbers greater than 1.05, the external drag of theconic-cowling models was less than drag
22、 of the solid bodyfor mass-flow ratios greater than 0.9. The data of reference4 indicnt e that the solid body is a low-drag conjuration atsupersonic speeds. The lower drags obtained with the coniccowlings indicnt e therefore that these also must be consid-ered as low-drag configurations.The variatio
23、n of external drag coefficient with mass-flowratio at Mm = 1.3 is shown for the various cowlings in figure12 by cross plotting the data of iigure 9. The increase inclrag with spillage is tierent for each coding and is greatestfor the conic cowling with sharp lips and least for the NACAl-series codin
24、g I. At m/mm =0.8, the three conic cowlingsand the parabolic cowling all have about the same drag.The NTACA l-series cowling has the greatest drag at all flowrates tested because of its high drag at mtium-flovr rate.The rate of increase of drag coticient with spillage forthe various cowlings is bett
25、er compared in figure 13 wherethe slopes of the curvw of figure 12 and similar ones forother Mach numbers are shown for each cowling. The slopeof the additive drag curve computed by a.w.ming one-dimensional flow is also shown as a function of Mach num-ber. The departure of the curves of figure 13 fr
26、om theadditive drag curve is caused by the reductions in codingpressure drag with spillage. The data indicate very littlechange in cowling pressure drag with spillage for the sharp-lip inlet and large reductions for the NACA l-series inlet.This trend is consistent with previous experiences with lead
27、-ing-edge suction for wings at angle of attack. Cowlingpressure distributions at several flow rates are shown inreference 3 for NTACA l-series cowlings.NACA 140-250 COWLTNGThe models with the NACA 140-250 cowling and therelated nonducted body B were tested for purpose of com-parison of results with
28、those results reported in reference 1.These models and those of reference 1 diflered only in fingeometry and overall length. The flight-test technique forobtaining the data w-as considerably ditlerent from that,reported herein. Comparison of the data of figures 9(f)and 10 with those presented in ref
29、erence 1 indicates that,when allowance is made for the differences in flu drag, themeasured drag coefficients of the present tests are essentiallythe same as those of refetence 1 for both the ducted andnonducted models. A comparison of the results for theducted models is shown in iigure 14 for sever
30、al Mach num-bers. The solid curve is the external drag coe.flicient,as presented in reference 1, which was extrapolateed tom/m. =1.0. The points are the mw+w.red values obtainedfor coding VI of this investigation. The long dashed curvewas obtained by correcting the data of reference 1 for thediffere
31、nce in fin-plus-interference drag. The difference infin-plus-interference drag was obtained by subtracting thetotal-minus-bme drag of nonducted model B from the total-minus-base drag of the solid body of reference 1.Comparison of the minimum drag of the NACA 140-250nose-inlet model with the minimum
32、drag of the AACA149300 model (cowling I) shows that the subsojj mAl (A5a)mrmd where M. is equal to or greater than Mm necessary tostart the inlet,A.=A, (A5b)The mass-flow ratio isP.A=V. A.mJm. = .p.A,Vm Ai (A6)Obviously the mass flow and internal drag can be properlyevaluated in the manner indicated
33、 only for the range of M.for which the flow follows the assumed pattern. The mini-mum Mach number for which the inlet and exit will bechoked depends on the relative size of the minimum area atthe inlet and exit and on the internal losses. The models ofthe present investigations were designed to chok
34、e at both theinlet and exit at Mach numbem horn slightly above sonic tothe maximum attained.One ducted model with pressure instrumentation and tele-meter was fight tested in order to determine the minimumMach number at which the assumed choking conditions m-isted at the inlet and exit. The measured
35、inlet and exit staticpressures together with the pitot stagnation pressure at theinlet were used to evaluate the internal drag and mass flowfor this model. The method of reducing these data was thesame as that discussed in reference 1 for ducted-nose-irdetmodels with telemeters.The pressure measurem
36、ents indicated that the inlet andexit were choked for values of M. greater than 1.o3 and1.08, respectively. The data of figure 7, however, show thatthe maw flow and internal drag computed according toequations (A3) to (A6) is in excellent agreement with themeasured values at all supersonic lMach num
37、bers. AtM. =0.9 the computed C,*., is still in good aggeementwith the measured value and the computed m/mm is about0.015 greater than that measured. It is, therefore, believedthat the method of calculation gives the correct values ofcD,fnt md m/m. at .1.03. lor Mach numbers from0.9 to 1.03, a small
38、error is introduced in the magnitude ofm/m. only.REFERENCESL Scars, R. I., and Merlet, C. F.: Flight Determination of the Drag Several NACA l-Series Nme Inlets With and Without Protrudingand Prcesure Recovery of an NACA 1-40-250 Nose Inlet at Central Bodies at High-Subsanio Mach Numhem and at a Maoh
39、Mach Numbers From 0.9 to 1.8. NACA TN 3218, 1955. (Su- Number of 1.2. NAC.4 TN 3436, 1955. (Supersedes NACApersedes NACA RM L50L18.) RM L9L23a.)2, Bnals, Donald D., Smith, Norman F., and Wright, John B.: The 4. Hart, Roger G., and Katz, Ellis R.: Flight Investigation at High-Development and Applknti
40、on of High-Critical-Speed Nose In- Subaonic, Transonic, and Supemonic Speeda to Determine Zero-Iets, NACA Rep. 920, 1948. (Supersedca NACA ACR L5F30a.) Lift Drag of Fin-Stabilized BodieE of Revolution Having Fine-3, Pendley, Rob&t E., and Robinson, Harold L.: An Investigation of nem Ratios of 12.5, 8.91, and 6.04 and Varying Positions of Maxi-mum Diameter. NACA RM L9130, 1949.707Provided 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-,-,-
