1、NASA TECHNICAL NOTEu-iCMNASA TN D-7205GOP Y- - EFFECT OF WING ASPECT RATIO AND FLAP SPANON AERODYNAMIC CHARACTERISTICS OFAN EXTERNALLY BLOWN JET-FLAP STOL MODELby Charles C. Smith, Jr.Langley Research CenterHampton, Va. 23665NATIONAL AERONAUTICS AND SPACE ADMINISTRATION WASHINGTON, D. C. AUGUST 1973
2、Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-1. Report No. 2. Government Accession No.NASA TN D-72054. Title and SubtitleEFFECT OF WING ASPECT RATIO AND FLAP SPAN ONAERODYNAMIC CHARACTERISTICS OF AN EXTERNALLYBLOWN JET -FLAP STOL MODEL7. Author(s)
3、Charles C. Smith, Jr.9. Performing Organization Name and AddressNASA Langley Research CenterHampton, Va. 2366512. Sponsoring Agency Name and AddressNational Aeronautics and Space AdministrationWashington, D.C. 205463. Recipients Catalog No.5. Report DateAugust 19736. Performing Organization Code8. P
4、erforming Organization Report No.L-875210. Work Unit No.760-61-02-0111. Contract or Grant No.13. Type of Report and Period CoveredTechnical Note14. Sponsoring Agency Code15. Supplementary Notes16. AbstractAn investigation has been conducted to determine the effects of flap span and wingaspect ratio
5、on the static longitudinal aerodynamic characteristics and chordwise and span-wise pressure distributions on the wing and trailing-edge flap of a straight-wing STOLmodel having an externally blown jet flap without vertical.and horizontal tail surfaces. Theforce tests were made over an angle-of-attac
6、k range for several thrust coefficients andtwo flap deflections. The pressure data are presented as tabulated and plotted chordwise- pressure-distribution coefficients for angles of attack of 1 and 16. Pressure-distributionmeasurements were made at several spanwise stations.17 Key Words (Suggested b
7、y Author(sj)STOLJet flapExternal blowing19. Security Oassif. (of this report)Unclassified18. Distribution StatementUnclassified - Unlimited20. Security Classif. (of this page) 21. No. of PagesUnclassified 13622. Price*$3.00For sale by the National Technical Information Service, Springfield, Virginia
8、 22151Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-EFFECT OF WING ASPECT RATIO AND FLAP SPANON AERODYNAMIC CHARACTERISTICS OF AN EXTERNALLYBLOWN JET-FLAP STOL MODELBy Charles C. Smith, Jr.Langley Research CenterSUMMARYAn investigation has been con
9、ducted to determine the effects of flap span and wingaspect ratio on the static longitudinal aerodynamic characteristics and chordwise andspanwise pressure distributions on the wing and trailing-edge flap of a straight-wing STOLmodel having an externally blown jet flap without vertical and horizonta
10、l tail surfaces.The force tests were made over an angle-of-attack range for several thrust coefficientsand two flap deflections. The pressure data are presented as tabulated and plotted chord-wise pressure-distribution coefficients for angles of attack of 1 and 16. Pressure-distribution measurements
11、 were made at several spanwise stations.The results of the investigation showed that reducing the flap span or wing aspectratio adversely affected the aerodynamic characteristics of the model which had fourengines located uniformly over the exposed span of the flap. The two-engine configurationwith
12、only the two inboard engines operating had about the same longitudinal aerodynamiccharacteristics as the configuration with all four engines operating. The spanwise liftdistribution of an externally blown jet flap is characterized by high peak loads, mainly onthe flaps behind each engine. There is a
13、 substantial spanwise lift carryover to stationsfar removed from the jet itself.INTRODUCTIONThe present investigation was a part of a general research program to provide some.fundamental information on the effects of geometric changes on the aerodynamic charac-teristics of an external-flow jet-flap
14、STOL model. A previous part of the program (ref. 1)studied the effects of vertical and longitudinal engine positions, jet-exhaust deflectors, andleading-edge and trailing-edge flap geometry on the aerodynamic characteristics of anexternally blown jet-flap (EBF) model. The object of the present part
15、of the program wasto determine the effects of flap span and wing aspect ratio on the aerodynamic character-istics of the model. The same basic model has been used in both parts of the program.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-This paper
16、 presents the effects of wing aspect ratio and flap span on the staticlongitudinal aerodynamic characteristics and the chordwise and spanwise pressure dis-tribution on the wing and flap of an EBF configuration without vertical or horizontal tailsurfaces. The model used in the investigation was power
17、ed by four simulated high-bypass-ratio turbofan engines and was equipped with an unswept, untapered wing havinga double-slotted trailing-edge flap and a leading-edge slat. The position of the enginesalong the span of the wing varied to provide uniform spacing over the exposed span of theflaps. The f
18、orce tests were made over an angle-of-attack range for several thrust coef-ficients and two flap deflections. The pressure-distribution tests were made for the sameflap deflections and thrust coefficients at angles of attack of 1 and 16.SYMBOLSThe data are referred to the stability-axis system with
19、the origin at the momentreference center location (0.40 mean aerodynamic chord). The pressure coefficients arebased on free-stream dynamic pressure. Measurements were made in the U.S. CustomaryUnits. They are presented herein in the International System of Units (SI) with the equiv-alent values in t
20、he U.S. Customary Units given parenthetically.A wing aspect ratiob wing span, m (ft)drag coefficient, Fp/qSlift coefficient, FL/qS_ incremental lift coefficient due to flap deflectionJftrimtrim m coefficient, CL + Mr circulation lift coefficient due to powerm pitching-moment coefficient, My/qScjj. g
21、ross-thrust coefficient, T/qSwing chord, 0.254 m (0.833 ft)Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-cnchord of rear element of trailing-edge flap, m (ft)r1wing-section normal-force coefficient, cp dx/cJnp - pCp pressure coefficient, pj-2cv van
22、e chord, m (ft)FA net axial force, N (Ib)FD drag force, N (Ib)FL lift force, N (Ib)F normal force, N (Ib)FR resultant force, FN2 + FA2, N (Ib)I tail length (assumed), m (ft)My pitching moment, m-N (ft-lb)p surface static pressure, N/m2 (lb/ft2)p free-stream static pressure, N/m2 (lb/ft2)q free-strea
23、m dynamic pressure, N/m2 (lb/ft2)S wing area, m2 (ft2)T measured gross engine thrust, N (Ib)W weightx longitudinal coordinate of airfoil, m (ft)y lateral distance from center line, measured perpendicular to plane ofsymmetry, m (ft)Provided by IHSNot for ResaleNo reproduction or networking permitted
24、without license from IHS-,-,-z airfoil surface ordinate, m (ft)a angle of attack, deg6f deflection of rear element of trailing-edge flap (positive when trailing edgeis down), deg5i jet turning angle, tan“* Jr , deg- A6V deflection of vane from wing chord plane, deg77 flap-system turning efficiency,
25、FR/TSubscripts:1 loweru upperMODEL AND APPARATUSFigure 1 presents a three-view drawing of the model with the aspect-ratio-7 wingand full-span flap. Figure 2 shows the planform arrangement of the wing and engines forA = 5.25 with full-span flap and A = 7 with both full-span and partial-span flaps. No
26、tethat in each case the engines were located so as to provide a uniform spacing over theexposed span of the flaps. Dimensional characteristics of the model are given in table I.The aspect-ratio-7, full-span-flap model was the same as that of reference 1, and the ver-tical and chordwise engine positi
27、on was the same as position 1 of reference 1 (see fig. 3).A detailed sketch of the wing leading-edge slat and trailing-edge flap assembly is shown infigure 4. An NACA 4415 airfoil was used on the wing. The airfoil sections for the vaneand flap of the trailing-edge flap assembly were identical, and t
28、heir coordinates are pre-sented in table n. Flap deflections 6f of 35 and 55 were obtained by using separate6fflap brackets for each case. In all tests with flaps deflected, 5V = -.The engines on the model represented high-bypass-ratio fan-jet engines andcompressed-air-driven turbines drove the fans
29、. The basic engine is illustrated infigure 5.In order to determine the chordwise and spanwise pressure distributions on thewing, pressure orifices were located on the upper and lower surfaces on the left wingand flap at eight spanwise stations. (See figs. 6 and 7.) In tests of the model withProvided
30、 by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-the reduced flap span and/or wing aspect ratio, only six spanwise locations of pressureorifices were used (1 to 6) because stations 7 and 8 were eliminated when the wing tipwas altered to obtain these configura
31、tions.The model was sting mounted on a six-component internal strain-gage balance inthe 9- by 18-m (30- by 60-ft) test section of the Langley full-scale tunnel.TESTS AND PROCEDURESIn preparation for the tests, engine calibrations were made to determine grossthrust as a function of engine rotational
32、speed in the static condition. These calibrationswere made with the engines mounted on the wing, bellmouth inlets installed, and trailing-edge flaps removed. The tests were then run by setting the engine rotational speed togive the desired thrust and holding these speeds constant over the angle-of-a
33、ttack range.Tests were made at zero airspeed to determine flap turning angles 6j and turningefficiencies 17 under static conditions. These tests and the wind-on tests were made at6f = 35 and 55.All wind-on force tests were made over an angle-of-attack range from -4 to 31at gross-thrust coefficients
34、Cn of 0, 2.05, and 4.10 for configurations having a wingaspect ratio of 7 and Cjj. = 0, 2.75, and 5.50 for a wing aspect ratio of 5.25. TheseCpi values correspond to the same thrust of the engines and differ only by being basedon a different wing area. The free-stream dynamic pressure for both the f
35、orce tests andthe pressure-distribution tests was 166 N/m (3.46 lb/ft2) which corresponds to an air-speed of 16.4 m/sec (54 ft/sec). The Reynolds number was 3.47 x 10 based on the wingchord.No wind-tunnel jet-boundary corrections were considered necessary since themodel was very small relative to th
36、e size of the test section.RESULTS AND DISCUSSIONStatic TurningSince the effectiveness of a jet-flap system is dependent to a large degree upon thecapability of the system for turning and spreading the jet exhaust efficiently, static turn-ing tests were made of all configurations included in the pre
37、sent investigation to identifythe relative performance of each. Results of these tests (see fig. 8) show there is very .little change in the jet turning angle due to changes in the aspect ratio of the wing and/orthe flap span. The ratio of the normal force to thrust Ff/T is plotted as a function oft
38、he ratio of net axial force to thrust -FA/T in figure 9. These data indicate that thelosses caused by turning and spreading of the jet were from 8 to 10 percent for 6f = 35Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-and from 35 to 40 percent for
39、6f = 55. The turning of the jet was better when thetrailing-edge flap was deflected 70 rather than 55 because the flap captured more ofthe jet engine exhaust. However, a trailing-edge-flap deflection of 55 instead of 70 wasused in the present investigation because the data of reference 1 indicate th
40、at undesirablelarge negative angles of attack would be associated with flight at 6f = 70.Wind-On DataFour engines.- The basic aerodynamic data for the model are presented in fig-ures 10 to 12 for 6f = 35 and figures 13 to 15 for 5f = 55. These data show that anincrease in thrust coefficient caused t
41、he usual increase in maximum lift coefficient andnose-down pitching moment.In order to show more clearly the effects of wing aspect ratio and flap span on thelongitudinal aerodynamic characteristics, the data of figures 10 to 15 have been replottedin terms of trim lift coefficient and drag coefficie
42、nt versus thrust coefficient C andpresented as figure 16. Comparison of the plots shows that there was little loss in trimlift coefficient with reduction in aspect ratio from 7 to 5.25 but that there is more thantwice as much loss in lift from reduction in flap span from full span to 0.75-span for t
43、heA = 7 wing. This comparison would suggest that there might be little lift carryover ontothe unflapped tip section of the wing. In order to investigate this point the data for theA = 5.25 wing were recomputed based on the area of the A = 7 wing. Comparison ofthe plots (fig. 16) shows that the unfla
44、pped tips added an increment of CL of 0.2 to 0.4(based on the total area of the A = 7 wing). Therefore, based on the area of the tipsthemselves, they added an increment of CL four times as great. On the basis of thisgross analysis of lift, it is apparent that the unflapped tips were causing an incre
45、ment oflift much greater than would normally be attributed to them.Presented in figure 17 are values of added circulation lift due to power CL r asa function of wing aspect ratio. These data were obtained from reference 2 for theinternal-flow jet-flap concept and from the present investigation for t
46、he EBF concept.The data from reference 2 show the increase in added circulation to be expected from agood internal-flow jet-flap system as the wing aspect ratio is increased. The data fromthe present investigation show, as expected, that the increase in CL r with aspect ratiois somewhat less for the
47、 EBF than for the internal-flow system.In figure 18 are values of CL r *or several different thrust coefficients and val-ues of ACL (incremental lift due to flap deflection) for 0 = 0 as a function of theratio of flap span to wing span. Also presented for comparison purposes are calculatedvalues of
48、AC from the method presented in reference 3. These data show that themeasured values of ACL at C = 0 are considerably lower than the calculated valuesfor a given flap span. The values of CL r fr the power-on tests are shown to varyProvided by IHSNot for ResaleNo reproduction or networking permitted
49、without license from IHS-,-,-almost linearly with flap span in the same manner as would be expected for circulationlift of an unpowered wing (ref. 3). It should be pointed out that the results presented infigure 18 are not only a function of flap span and wing aspect ratio, but also of engineposition; and the present da
