1、.NASA TN D-1620 J” TECHNICAL NOTE D- 1620 EFECT OF CROSS-SECTION SHAPE ON THE AERODYNAMIC CHARACTERISTICS OF BODIES AT MACH NUMBERS FROM 2.50 TO 4.63 By Dennis E. Fuller, David S. Shaw, and Donald L. Wassum Langley Research Center Langley Station, Hampton, Va. NATIONAL AERONAUTICS AND SPACE ADMINIST
2、RATION WASHINGTON March 1963 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NATIONAL AERONAUTICS AND SPACE ADMINISTRATION TECHNICAL NOTE D-1620 EFFECT OF CROSS-SECTION SHAPE ON TRE AERODYNAMIC CHARACTERISTICS OF BODIES AT By Dennis E. MACH NUMBERS F
3、ROM 2.50 TO 4.63 Fuller, David S. Shaw, and Donald L. Wassum SUMMARY An investigation has been made in the high Mach number test section of the Langley Unitary Plan wind tunnel to determine the aerodynamic characteristics of several bodies that differed only in cross section. All of the bodies had a
4、 fine- ness ratio of 10 and the same longitudinal cross-sectional area distribution. The cross-sectional shapes tested were a circle; ellipses with width-height ratios of 1 1 -*l, lF:l, and 2:l; and flat-bottom and flat-top semiellipses. In addition, flat- 2 bottom and flat-top bodies with triangula
5、r-shaped cross sections and rounded corners were tested. and at a Reynolds number per foot of 2.3 X 10 6 . The tests were performed at Mach numbers from 2.50 to 4.63 The results indicate that increasing the width-height ratio of the bodies provides substantial increases in lift and in lift-drag rati
6、o. In addition, the results for the flat-top body with an unsymmetrical nose indicates the possibility of combining positive pitching moments at zero angle of attack with high lift-drag ratios. INTRODUCTION The fuselage comprises a major portion of the volume of supersonic aircraft, missiles, and li
7、fting space vehicles and, as such, should be designed as effi- ciently as possible to enhance their stability and performance characteristics. Some exploratory work has been performed on fuselage design for large supersonic aircraft (e.;., ref. 1) and considerable tests have been performed on cross-
8、 sectional body shapes at Mach numbers near 2.0 and 3.9 (e.g., refs. 2 and 3). was believed desirable, however, to more accurately define Mach number effects for similar bodies in this Mach number range. It Accordingly, a series of eight bodies with various cross-section shapes were designed. The cr
9、oss-section shapes tested were a circle; ellipses with width- height ratios of and flat-bottom and flat-top semiellipses. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-In addition, flat-bottom and flat-top bodies with triangular-shaped cross sectio
10、n; and rounded corners were tested. Each body in the series had a fineness ratio of 10 and the same longitudinal cross-sectional area distribution. The tests were performed in the Langley Unitary Plan wind tunnel at Mach nm bers from 2.50 to 4.63, at angles of attack from -60 to l7O, and at a Reynol
11、ds nmkr per foot of 2.5 x 106. SYMBOLS The aerodynamic force and moment data are referred to the stability-axis sys, tem (fig. 1) with the moment center at 50 percent of the body length (fig. 2). Symbols used are defined as follows: body base area, sq ft semimajor axis of elliptic cross section, in.
12、 semiminor axis of elliptic cross section, in. drag coefficient, Drag/qA chamber drag coefficient, Chamber drag/qA minimum drag coefficient lift coefficient, Lift/qA slope of lift curve at pitching-moment coefficient, Pitching moment/qAd slope of pitch curve at a = 00, ah/ thus, these bodies are eff
13、ectively cambered. The aft end of each model bras PROCEDURE Test Conditions 3 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-A 1/16-inch-wide transition strip of No. 60 carborundum grains (nominal diam- eter of 0.012 inch) was placed around the fore
14、body 1 inch aft of the nose of each model in order to assure turbulent flow. chosen by the methods of ref. 4. ) The dewpoint, measured at stagnation pressure, was maintained below -300 F in order to assure negligible condensation effects. (The size of the transition grains was 1 I Measurements and M
15、ethods Aerodynamic forces and moments on the models were measured by means of an internal electrical strain-gage balance. The balance was attached to a sting which, in turn, was rigidly fastened to the tunnel support system. The angle of attack varied from about -6 to 17 and the angle of sideslip wa
16、s maintained at approximately Oo. Balance-chamber pressure, used in computing chamber drag, was measured by means of six static-pressure orifices located in the vicinity of the strain-gage balance. CORRECTIONS AND ACCURACY I The angles of attack have been corrected for both tunnel flow angularity an
17、d deflection of the model and sting support system due to aerodynamic loads. The drag data have been adjusted to correspond to free-stream static pressure in the balance chamber. The magnitudes of these chamber-drag-coefficient corrections are shown in figure 3. Based on balance calibrations and rep
18、eatability of data, it is estimated that .at low angles of attack the various measured quantities are accurate within the following limits: CD. . ko.002 cD,c . 0.0 CL kO.025 C,. . kO.014 a, deg kO.10 M = 2.50; M = 2.96 kO.Ol5 M = 3.95; M = 4.63 ko.050 RESULTS AND DISCUSSION Lift Characte ri st i c s
19、 The basic aerodynamic characteristics in pitch are presented in figures 4 to 7 and summarized in figure 8. a = Oo of a body, as would be expected from the conclusions of references 2 and 3. In addition, it appears that except for the flat-top and flat-bottom triangular and semielliptical The data s
20、how that the lift-curve slope at for a given Mach number increases with an increase in width-height ratio is directly proportional to the width-height ratio Ch 4 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-configurations. cross section, the flat-
21、top and flat-bottom triangular and semielliptical config- urations have a greater value of than might be expected from their geometric dimensions. The two flat semielliptical configurations, as previously mentioned, have nonsymmetrical forebodies which result in a positive lift coefficient at a = Oo
22、 for the flat-top configuration and a negative lift coefficient at a =%O for the flat-bottom configuration even though, at the lower test angles of attack (up to a = 6O), their lift-curve slopes are approximately the same. The greater lift-curve slopes of the flat-top and flat-bottom semielliptical
23、configurations are at least partly due to their greater nose angle. (See fig. 9. ) When compared with the body having a circular Cb 0 With the exception of the flat-top and flat-bottom semielliptical bodies, C that is, when the values of Ch increase, the values of Cma also increase. Thus, the ellips
24、e with a width-height ratio of r-1 has the least bottom semielliptical configurations have the greatest C, values. The flat- top semielliptical body, because of its upswept nose, provides a positive pitching moment at a = Oo, whereas the flat-bottom semiellipse effects a nega- tive pitching moment a
25、t a = Oo. For all test configurations, an increase in Mach number results in a decrease in appears to be greater with increasing width-height ratio of the bodies. C values, and the flat-top and flat- 2 ma Cma; however, the rate of decrease in Cma Drag Characteristics It would be expected that the wa
26、ve drag for all the elliptical models with symmetrical forebodies would be nearly the same, and any differences in minimum drag coefficient could be attributed to changes in skin-friction drag incurred by increases in wetted area. ellipsej, which has the least wetted area of any of the bodies, shoul
27、d have the lowest minimum drag-coefficient values. However, the triangular configurations at Mach numbers of 2.50 and 2.96 have the lowest minimum drag coefficients of any of the test configurations. This result is not in accord with the results of similar configurations of references 2 and 3, and t
28、he reason for this discrepancy is not known. The flat-top and flat-bottom semielliptical bodies produced the greatest values of CD,min since they have the greatest wetted area and also the largest nose angle of any of the test Configurations. Thus, the body with the circular cross section (a 1:l 5 P
29、rovided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Lift-Drag Ratios The maximum lift-drag ratios for the bodies with uncambered noses increase with increase in width-height ratio and occur at lower angles of attack as the width-height ratio increases. Th
30、ere is little difference in (L/D), for the flat-top semiellipse and the ellipse with a width-height ratio of 2:l primarily because of the increase in CD,min for the flat-top body; however, (L/D)mm for the flat-bottom semiellipse is considerably greater than that for any of the other configurations.
31、(This result is in agreement with the data of refs. 2, 3, and 5.) The higher (L/D)- for the flat-bottom semiellipse is believed to be due to the sharp bottom edges of this configuration which result in a high- pressure fi;.ld on the lower side, whereas the curved sides of the other configu- rations
32、have a relieving effect. This phenomenon may also be noted at M= 2 by comparing the sharp-cornered, triangular-cross-section configurations of refer- ence 2 with the similar but rounded-corner configurations of. reference 3, and at M = 3.9 by comparing the data of this paper with that of reference 2
33、. In order to more clearly define the relative performance of the flat-top and flat-bottom semielliptical configurations, the lift-drag ratios for these configu- rations have been plotted against lift coefficient at each test Mach number and compared with the data for the basic body with a circular
34、cross section. fig. 10.) At very low-lift coefficients (up to ference in the flat-bottom body exhibits appreciably greater values of for the other two configurations. Although the flat-top body has L/D values below those for the flat-bottom body, it exhibits greater than those for the body with a ci
35、rcular cross section. (See CL SJ 0.5), there is little dif- L/D for the three bodies shown; however, at higher lift coefficients L/D than those shown L/D values significantly CONCLUDING REMARKS An investigation has been conducted in the Langley Unitary Plan wind tunnel at Mach numbers from 2.50 to 4
36、.63 to determine the aerodynamic characteristics of several bodies that differed only in cross-sectional shape. The results indicate that increasing the width-height ratio of the bodies provides substantial increases in lift and in lift-drag ratio. In addition, the results for the flat-top body with
37、 an unsymmetrical nose indicate the possibility of combining positive pitching moments at zero angle of attack with high lift- drag ratios. Langley Research Center, National Aeronautics and Space Administration, Langley Station, Hamptdn, Va., December 17, 1962. 6 Provided by IHSNot for ResaleNo repr
38、oduction or networking permitted without license from IHS-,-,-I REFERENCES I 1. Gregory, Donald T., and Kelly, Thomas C.: Aerodynamic Characteristics At Mach Numbers From 2.30 to 4.30 of a Canard Configuration Having Varied Body I Shapes. NASA IM X-171, 1959. I 2. Jorgensen, Leland H.: Inclined Bodi
39、es of Various Cross Sections at Supersonic , Speeds. NASA MEMO 10-3-58A, 1958. 3. Carlson, Harry W., and Gapcynski, John P.: An Experimental Investigation at a Mach Number of 2.01 of the Effects of Body Cross-Section Shape on the Aero- dynamic Characteristics of Bodies and Wing-Body Combinations. NA
40、CA RM L55E23, 1955- 4. Braslow, Albert L., and Knox, Eugene C. : Simplified Method for Determination of Critical Height of Distributed Roughness Particles for Boundary-Layer Transition at Mach Numbers From 0 to 5. NACA TN 4363, 1958. 5. Jack, John R., and Moskowitz, Barry: Aerodynamic Characteristic
41、s of Two Flat- Bottomed Bodies at Mach Number of 3.12. NACA RM E53Lllb, 1954. 7 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-I I 8 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-4 f 1 n I I 1 I “
42、* d -8 rl rn r cu rn 9 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-a, deg Figure 3.- Variation of chamber-drag coefficient with angle of attack. 10 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
43、I I n .rl n m 8 V x a B k 11 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-12 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-I Provided by IHSNot for ResaleNo reproduction or networking permitted w
44、ithout license from IHS-,-,-4. L D - 4. 4. 3. 3. 2. 2. 2. 1. 1. (d) Lift-drag ratio. Figure 4. - Concluded. 14 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-m Provided by IHSNot for ResaleNo reproduction or networking permitted without license from
45、 IHS-,-,-h P u I ln 16 Provided 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-,-,-4 4 4 2 L -2 0 2 1 1 (d) Lift-drag ratio. Figure 5. - Concluded. I 18 Provided by
46、 IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-I I Provided 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-,-,-0 I I I I 21
47、Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-a, deg (d) Lift-drag ratio. Figure 6.- Concluded. I 22 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-I I 23 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-i 24 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-C La . 2.0 2.4 2.8 3.2 3.6 4.0
