1、/NASA TECHNICAL NOTE NASA TN D-3088_0 j-cO, _ N66-12138_ (ACCESSION NUMBER (THRU|(NASA GR OR TMX OR AD NUMBER) (CATI=_ORY),=l:z AERODYNAMIC CHARACTERISTICSOF SPHERICALLY BLUNTED CONESAT MACH NUMBERS FROM 0.5 TO 5.0by Robert V. OwensGeorge C. Marshall Space Flight CenterHuntsville, Ala.NATIONALAERONA
2、UTICSANDSPACEADMINISTRATIONWASHINGTON,D. C. - DECEMBER1965/ / /Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NASA TN D-3088AERODYNAMIC CHARACTERISTICS OF SPHERICALLY BLUNTED CONESAT MACH NUMBERS FROM 0.5 TO 5.0By Robert V. OwensGeorge C. Marshall S
3、pace Flight CenterHuntsville, Ala.NATIONAL AERONAUTICSAND SPACE ADMINISTRATIONFor sale by the Clearinghouse for Federal Scientific and Technical InformationSpringfield, Virginia 22151 - Price $3.00Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TABLE
4、 OF CONTENTSPageINTRODUCTION iMODE LS AND APPARATUS 2ACCURACY OF DATA 3RESULTS AND DISCUSSION. . 4Normal Force Coefficient Slope . 4Center of Pressure . 5F orebody Drag Coefficients . 6CONC LUSIONS . 7APPENDIX . 45REFERENCES. . 51,UlProvided by IHSNot for ResaleNo reproduction or networking permitte
5、d without license from IHS-,-,-LIST OF ILLUSTRATIONSzTable PageI Test Conditions . 2Figure Title1 Nomenclature and Model Characteristics 82 Cone Families Tested . 93 Typical Schlierens l04 Model and Balance System Used in 7 x 7-InchTunnel Tests . 1i5 Model and Balance System Used in i4 x i4-InchTunn
6、el Tests . i26 Diagrammatic Representation of Transonic FlowConfigurations for Cones . 137 Variation of Normal Force Coefficient Slopewith Mach Number for Various Cones (d/D = 0) 148 Variation of Normal Force Coefficient Slopewith Math Number for Various Cones (d/D = 0.4) . 159 Variation of Normal F
7、orce Coefficient Slopewith Mach Number for Various Cones (d/D = 0.8) . 16i0 Variation of Center of Pressure with MachNumber for Various Cones (d/D= 0.0) . 17li Variation of Center of Pressure with MachNumber for Various Cones (d/D= 0.4) . 1812 Variation of Center bf Pressure with MachNumber for Vari
8、ous Cones (d/D = 0.8) . i9i3 Variation of Foredrag Coefficient with MachNumber for Various Cones (d/D= 0r 0). 20ivProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-LIST OF ILLUSTRATIONS (Contd)Figure Title Page14 Variation of Foredrag Coefficient with
9、MaehNumber for Various Cones (d/D = 0.4) . 21i5 Variation of Foredrag Coefficient with MachNumber for Various Cones (d/D = 0.8) , . , 22i6 Variation of Normal Force Coefficient Slope withCone Half Angle and Bluntness at M = 0.68 . 2317 Variation of Normal Force Coefficient Slope withCone Half Angle
10、and Bluntness at M = 0.94 2418 Variation of Normal Force Coefficient Slope withCone Half Angle and Bluntness at M = i. 05 . 2519 Variation of Normal Force Coefficient Slope withCone Half Angle and Bluntness at M = i. 30 . 2620 Variation of Normal Force Coefficient Slope withCone Half Angle and Blunt
11、ness at M = i. 50 . 2721 Variation of Normal Force Coefficient Slope withCone Half Angle and Bluntness at M = i. 97 . 2822 Variation of Normal Force Coefficient Slope withCone Half Angle and Bluntness at M = 2.75 . 29 23 Variation of Normal Force Coefficient Slope withCone Half Angle and Bluntness a
12、t M = 4. 00 . 3024 Variation of Center of Pressure with Cone HalfAngle and Bluntness at M = 0.68 3125 Variation of Center of Pressure with Cone HalfAngle and Bluntness at M = 0.94 3226 Variation of Center of Pressure with Cone HalfAngle and Bluntness at M = i. 05 . 3327 Variation of Center of Pressu
13、re with Cone HalfAngle and Bluntness at M = i. 50 . 34VProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-LIST OF ILLUSTRATIONS (Contd)Figure Title Page28 Variation of Center of Pressure with Cone HalfAngle and Bluntness at hi = i. 97 . 3529 Variation o
14、f Center of Pressure with Cone HalfAngle and Bluntness at M = 2.75 . 3630 Variation of Center of Pressure with Cone HalfAngle and Bluntness at hi = 4.00 . 3731 Variation of Foredrag Coefficient with Cone HalfAngle and Bluntness at M = 0.68 . 3832 Variation of Foredrag Coefficient with Cone HalfAngle
15、 and Bluntness at M = 0.94 3933 Variation of Foredrag Coefficient with Cone HalfAngle and Bluntness at M = i. 05 4034 Variation of Foredrag Coefficient with Cone HalfAngle and Bluntness at hi = l. 50 . 4135 Variation of Foredrag Coefficient with Cone HalfAngle and Bluntness at hi = l. 97 . 4236 Vari
16、ation of Foredrag Coefficient with Cone HalfAngle and Bluntness at M = 2.75 4337 Variation of Foredrag Coefficient with Cone HalfAngle and Bluntness at M = 4.00 . 44A-i Relationship Between Geometric Parameters ofSpherically Blunted Cones . 46A-2 Relationship Between Geometric Parameters ofSpherical
17、ly Blunted Cones . 47A-3 Hypersonic Newtonian Normal Force Coefficient Slopefor Cones of Varying Geometry 48viProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-LIST OF ILLUSTRATIONS (Contd)Figure Title PageA-4 Hypersonic Newtonian Centers of Pressure f
18、or Conesof Varying Geometry 49A-5 Hypersonic Newtonian Wave Drag for Cones ofVarying Geometry 50viiProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-DEFINITION OF SYMBOLSSymbol DefinitionA Area based on diameter D, (in 2)CDb Base drag coefficient (_)CD
19、f Fore drag coefficient (CDt- CDb)CDt Total drag“ coefficient “CN Normal force coefficient slope l_ad )Dt Total drag (lb)D Base diameter (in.)d Diameter of spherical nose segment at station of tangency (d/2r)d Bluntness ratioDe Cone half angle (deg.)L Length of bodyL/D Fineness ratioM Mach numberM M
20、inimum Mach number for shock attachment for pointed conessN Normal force ( lb. )P Free stream static pressure (psi)Pb Base pressure (psi)Pt Total pressure (psi)q Dynamic pressure (psi)viiiProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-DEFINITION OF
21、SYMBOLS (Contd)Symbol DefinitionRn Reynlds number( Vfi_PL )r Radius of spherical nose (in.)T t Total temperature ( F)CP/D Center of pressure location (from base)Angle of attack ( deg. )ixProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-L AERODYNAMICCH
22、ARACTERISTICSOFSPHERICALLYBLUNTEDCONES“ ATMACHNUMBERSFROM0.5TO5.0SUMMARY . . ,/_/_F5 mic /An expemmental investigation has been made to determine the aerodynacharacteristics of several cones at Mach numbers from 0.5 to 5 0 and to estab!ish the effects of bluntness. The results of the investigation s
23、how that the abrupt changes /in aerodynamic parameters in the transonic region are closely related to the devel- /opment of the shock wave pattern. Those parameters most affected were the normal /force coefficient slope and the forebody drag coefficient. The center of pressure, on the other hand, re
24、mained relatively stationary for cones with moderate half- . . Iangles, except at very near sonic Mach number. The effects of bluntness were mini_real at Mach numbers smaller than those required for shock attachment on pointed /cones. At higher Mach numbers, bluntness effects were sizeable for the s
25、maller cone half-angles, but negligible for the larger ones. In every case, increases in bluntness as well as cone angle increased the downstream movement of, the, center of pressure. _)/.c. /y/ _)INTRODUCTIONThe inadequacy of theory in predicting the aerodynamic characteristicsof blunted cones accu
26、rately creates a need for a thorough experimental investi-gation. Such a study has been especially desirable in the transonic Mach numberrange where no practical theory applies.This experimental program was initiated to satisfy this need and to providedesigners of blunted-cone vehicles with data fro
27、m a wide range of parametric varia-tions. The normal force coefficient slopes, center of pressure locations, and fore-body drag coefficients were determined for twelve cones over a Mach number rangefrom 0.5 to 5.0. The models used in the investigation were grouped into fourfamilies of different cone
28、 angles, each having three different nose bluntness ratios.Eight models with two additional bluntness ratios were tested up to M= 2.0 i.From this wide range of geometric parameters, the effects of bluntness and coneangle could be deduced in addition to those of Mach number. The tests were con-ducted
29、 at the NASA, Marshall Space Flight Center, i4 x 14-inch trisonic and the7 x 7-inch supersonic wind tunnels.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MODELSANDAPPARATUSThe investigation was conducted in three series of tests. Transonic and supe
30、r-sonic tests were run in the trisonic wind tunnel over Mach number ranges from 0.47to i. 93 and 2.74 to 4.96, respectively. To establish the continuity and validity of thedata, a supersonic test covering the Mach range from i. 58 to 4. 39 was conducted in the7 x 7-inch supersonic wind tunnel. The c
31、haracteristic air properties during operationof both facilities are given in Table 1.TABLE ITEST CONDITIONSWind Tunnel Test Facility M Pt Tt Rn/in“(psia) ( F) x 10 -614 x i4 Transonic 0.5 22 i20 0.3520.7 0. 4360.85 0.489O. 95 O. 5101. i5 O. 5351.25 _ O. 535I. 43 22 I V 0.5i3i. 93 28 i20 0.590i4 x i4
32、 Supersonic 2.74 30 i20 0.4022.99 45 i20 0.55i3.48 75 140 0.6574.00 i05 140 0.7174.45 i05 180 0.55i4.96 I05 200 0.4027 x 7 Supersonic i. 58 14.5 90 0.350i.99 0.3062.44 0.2462.99 I i 0. i873.26 0. i623.60 I _ 0. i373.89 r I- ol174.39 i4.5 90 0.0942Provided by IHSNot for ResaleNo reproduction or netwo
33、rking permitted without license from IHS-,-,-Twelve cone models representing four families of different cone half-angles of10, i3.32, 25, and 50 degrees were tested at all of the above Maeh number ranges.The three cones within each family had bluntness ratios of 0, 0.4, and 0.8;i. e., onewas pointed
34、, while the other two were trtfmcated and tipped with spherical segments.Eight models, representing two additional bluntness ratios (d/D = 0.2 and 0.6) foreach of the cone families, were tested in only the Mach number range from 0.43 to1.93. 1 The geometric characteristics of the models and nomencla
35、ture are given inFigure i, and the configurations tested are represented in the diagrams of Figure 2.Some representative Schlieren pictures of the test models are shown in Figure 3 forvarious Mach numbers.All models were mounted on a sting which contained a system of interchangeablestrain gauge beam
36、s as parts of a three:component balance. Because of limitationson the model size, the balance system used in the 7 x 7-inch tunnel test was housedwithin a faired portion of the sting aft of the model base. The balance assembly ofthe 14 x 14-inch tunnel, however, could be fitted conventionally to the
37、 forward end ofthe sting projecting into the models. Composition X-ray pictures of both balancesystems are shown in Figures 4 and 5.ACCURACYOFDATAAll force and base pressure measurements were taken over the angle of attackrange from approximately -4 to i0 , which was traversed automatically in both
38、tunnelfacilities. Because of the sting effects on base pressures, the accuracy of the totaldrag is somewhat uncertain. By subtracting the base drag, which was determined froma base pressure measurement, the invalid component is removed. The resulting foredrag, which consists of wave drag and skin fr
39、iction drag, should be accurate at thedesignated Reynolds numbers.Data reduction of the strain gauge and base pressure readings were achievedthrough digitizing the analog signals, punching values into data cards, and finallyprocessing the card data into coefficient form by computer.The accuracy of t
40、he data, estimated by several means, takes into considera-tion the following:a. Data scatterb. Repeatability of a given test pointc. Agreement of data measured by several different strain gaugesd. Level of accuracy of previous testse. Continuity between the data from the two different test facilitie
41、s.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Based on these indications, the estimated accuracy of the faired data isCP _ 0 02, CN=0.04, CDf= 0.01.D “RESULTSANDDISCUSSIONThe results of the test are presented in a manner to enable the study of th
42、evariation of normal force coefficient slope, center of pressure, and forebody dragcoefficient with Mach number for various cone configurations and also to show theeffects of cone half-angle (_) and bluntness (d/D). The basic data variations withMach number are given in Figures 7 through 15 for vari
43、ous cone half-angles andare grouped according to bluntness. To provide data for the lower end of the Machnumber spectrum, the results of the transonic test published earlier 1 are in-cluded. Results from various other sources 2,3 are also incorporated whenpossible. The interpolated values for variou
44、s intermediate cone half-angles, repre-sented by dashed lines, are also indicated in the above figures. By presenting cross-plots of the aerodynamic characteristics versus cone half-angles at various Machnumbers Figures t6 through 37), the effects of cone angle and bluntness can bestudied directly.
45、Here again the data from other sources, notably from Reference3, provided complementing key points.NormalForceCoefficient SlopeWith a few exceptions, the linearity of normal force coefficient with angle ofattack was maintained to approximately 4 degrees. The normal force coefficientslopes at zero an
46、gle of attack are presented in Figures 7 through 9 for three degreesof bluntness. For zero bluntness cones, the values of normal force coefficientslope remain relatively constant once the local flow becomes supersonic, and thelevels agree well with hypersonic Newtonan theory, even for Mach numbers l
47、essthan 5.0. For blunted cones, however, the values of normal force coefficientsslope for moderate cone half-angles decline at the beginning of the supersonic Mathnumber range, but tend to remain constant or increase slightly at the end of thetest Mach number range. An increase in C N values with st
48、ill higher Mach numberswould be necessary to obtain agreement withhypersonic Newtonan values.For Mach numbers smaller than M (minimum Mach number for shockattachment for pointed cone) , no significanSt changes in CN_ were observed as thebluntness was increased from 0 to 0.4. For cones up to E = 30 , bluntness ratios4Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Of 0.8, however, produced very pronounced CNa peaks which o
