1、NASA I TP 1419 . c. 1 8- ,NASA Technical Paper. 1419 Low-Speed Wind-Tunnel Investigation of Flight Spoilers as Trailing-Vortex- Alleviation Devices on a Transport Aircraft Model Delwin R. Crootn APRIL 1979 NASA Provided by IHSNot for ResaleNo reproduction or networking permitted without license from
2、 IHS-,-,-TECH LIBRARY KAFB, NM NASA Technical Paper 1419 Low-Speed Wind-Tunnel Parametric Investigation of Flight Spoilers as Trailing-Vortex- Alleviation Devices on a Transport Aircraft Model Delwin R. Croom Langley Research Center Hampton, Virginia National Aeronautics and Space Administration Sci
3、entific and Technical Information Office 1979 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SUMMARY An investigation was made in the Langley V/STOL tunnel to determine, by the trailing-wing sensor technique, the effectiveness of 11 combinations of
4、the existing flight-spoiler segments on a jumbo-jet transport aircraft model when they were deflected as trailing-vortex-alleviation devices. All 11 of the flight-spoiler configurations investigated were effective in reducing the induced rolling moment on the trailing model by as much as 18 to 67 pe
5、rcent at a distance of 7.8 transport wing spans behind the transport aircraft model. The present investigation is an extension of earlier wind-tunnel and flight tests which showed that the existing flight spoilers on the jumbo-jet aircraft can be used as effective trailing-vortex-alleviation devices
6、. Essentially all of the reduction in induced rolling moment on the trailing- wing model was realized at a spoiler deflection of 45O for single-spoiler con- figurations, 30 for two-spoiler configurations, and 15O for both the three- and four-spoiler configurations. Of the 11 light-spoiler configurat
7、ions investigated, the most promising configuration for trailing-vortex abatement on the jumbo-jet aircraft appears to be the three inboard flight spoilers deflected 15O. This configuration reduced induced rolling moment on the trailing-wing model by 65 percent and increased drag coefficient on the
8、transport aircraft model by about 0.012 at a trim lift coefficient of 1.2. INTRODUCTION The strong vortex wakes generated by large transport aircraft are a poten- tial hazard to smaller aircraft. The National Aeronautics and Space Administra- tion is involved in a program of model tests, flight test
9、s, and theoretical stud- ies to investigate aerodynamic means of reducing this hazard (ref. 1). Results of recent investigations have indicated that the trailing vortex behind an unswept-wing model (ref. 2) or a swept-wing transport model (ref. 3) can be attenuated by a forward-mounted spoiler. It w
10、as also determined by model tests (refs. 4, 5, and 6) and verified in full-scale flight tests that there are several combinations of the existing flight spoilers on both the jumbo-jet transport aircraft (ref. 7) and a medium-range wide-body tri-jet transport air- craft (ref. 8) that are effective as
11、 trailing-vortex-alleviation devices. The approach used in references 2 to 6 to evaluate the effectiveness of vortex- alleviation devices was to simulate an airplane flying in the trailing vortices of another larger airplane and to make direct measurements of rolling moments induced on the trailing
12、model by the vortices generated by the forward model. The technique used in the full-scale flight tests (refs. 7 and 8) was to pene- trate the trailing-vortex wake behind a Boeing 747 aircraft (ref. 7) and behind a Lockheed L-1011 aircraft (ref. 8) with a Cessna T-37 aircraft and to evaluate Provide
13、d by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-the roll response and roll attitude of the Cessna T-37 aircraft as an index of the severity of the trailing-vortex encounter. Since there were a limited number of flight-spoiler combinations investi- gated in
14、reference 4, the purpose of the present investigation is to determine whether other flight-spoiler combinations on the jumbo-jet transport aircraft model would give greater trailing-vortex alleviation than those reported in reference 4. The direct-measurement technique described in references 2 to 6
15、 was used with the trailing-wing model at 7.8 transport wing spans behind the transport aircraft model. For the full-scale transport airplane, this would represent a downstream distance of 0.25 nautical mile. The use of commercial airplane designations in this report does not consti- tute an officia
16、l endorsement of such products or manufacturers, either expressed or implied, by the National Aeronautics and Space Administration. SYMBOLS All data are referenced to the wind axes. The pitching-moment coefficients are referenced to the quarter-chord of the wing mean aerodynamic chord. wing span, m
17、Drag drag coefficient, - qs, Lift lift coefficient, - qsw Trailing-wing rolling moment trailing-wing rolling-moment coefficient, qSTWbTW Pitching moment pitching-moment coefficient, qww wing chord, m wing mean aerodynamic chord, m horizontal-tail incidence, referred to fuselage reference line (posit
18、ive direction, trailing edge down), deg free-stream dynamic pressure, Pa 2 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-S wing area, m2 x,Y,Z system of axes originating at left wing tip of transport aircraft model (see fig. 1) x,y,z longitudinal,
19、lateral, and vertical dimensions measured from trailing edge of left wing tip of transport aircraft model, m a angle of attack of fuselage reference line (wing incidence is 2O rela- tive to fuselage reference line), deg Subscripts: IEiX maximum Tw trailing-wing model W transport aircraft model MODEL
20、 AND APPARATUS A three-view sketch and the principal geometric characteristics of the 0.03-scale model of the jumbo-jet transport aircraft are shown in figure 1. Figure 2 is a photograph of the transport aircraft model sting mounted in the Langley V/STOL tunnel. The fuselage, empennage, trailing-edg
21、e flaps, and leading-edge devices of this model were the same as those used in references 3 and 4. The wing had flight spoilers typical of this type of aircraft. Fig- ure 3 is a sketch showing the location and numbering of the flight-spoiler seg- ments on the transport aircraft model. Photographs of
22、 9 of the 11 flight- spoiler configurations investigated are presented in figure 4. (Not shown are two single-spoiler configurations, segment 2 and segment 3.) A photograph and dimensions of the unswept trailing-wing model installed on the traverse mechanism are presented in figure 5. The trailing m
23、odel has a span and aspect ratio typical of small-size transport aircraft. The test section of the Langley V/STOL tunnel has a height of 4.42 m, a width of 6.63 m, and a length of 14.24 m. The transport aircraft model was sting mounted near the forward end of the tunnel test section on a six-compone
24、nt strain-gage balance system which measured the forces and moments. The angle of attack was determined from an accelerometer mounted in the fuselage. The trail- ing model was mounted on a single-component strain-gage roll balance, which was attached to a traverse mechanism capable of moving the mod
25、el both laterally and vertically. (See fig. 5.) The lateral and vertical positions of the trailing model were measured by outputs from digital encoders. This entire traverse mechanism could be mounted to the tunnel floor at various tunnel longitudinal positions downstream of the transport aircraft m
26、odel. 3 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TESTS AND CORRECTIONS Transport Aircraft Model All tests were made at a free-stream dynamic pressure in the tunnel test section of 430.9 Pa which corresponds to a velocity of 27.4 m/sec. The Rey
27、nolds number for the tests was approximately 4.7 x 1 O5 based on the wing mean aero- dynamic chord. Transition strips approximately 0.30 cm wide of No. 60 abrasive grit were placed 2.54 cm back from the leading edge of the wing, whereas natural transition was used elsewhere. The basic longitudinal a
28、erodynamic characteris- tics were obtained through an angle-of-attack range of approximately -4O to 24O. All tests were made with leading-edge devices extended, landing gear down, and landing flaps deflected 30. Blockage corrections were applied to the data by the method of reference 9. Jet-boundary
29、 corrections to the angle of attack and the drag were applied in accordance with reference 10. Trailing-Wing Model The trailing-wing model and its associated roll-balance system were used as a sensor to measure the induced rolling moment caused by the vortex flow downstream of the transport aircraft
30、 model. No transition grit was applied to the trailing model. The trailing model was positioned near the aft end of the tunnel test section (7.8 transport wing spans behind the transport aircraft model), and the traverse mechanism was positioned laterally and vertically so that the trailing vortex w
31、as near the center of the mechanism. The trailing vortex was probed with the trailing model. A large number of trailing-wing rolling-moment data points (usually from 50 to 100) were obtained from the lateral traverses at several vertical locations to ensure good definition of the vortex wake so that
32、 the maximum trailing-wing rolling-moment coefficient could be determined. In addition, certain test conditions were repeated at selected intervals during the test period and the data were found to be repeat- able. All trailing-wing rolling-moment data were obtained with the transport aircraft model
33、 at a trimmed lift coefficient of 1.2 (C,ti = 1.2). RESULTS AND DISCUSSION Transport Aircraft Model The longitudinal aerodynamic characteristics of the transport aircraft model with 11 different flight-spoiler configurations deflected symmetrically through a range of Oo to 45O are presented in figur
34、es 6 to 16. Table I lists the 11 spoiler configurations. These data (figs. 6 to 1 6) were obtained with the hori- zontal tail set at Oo (it = Oo) . Below the stall, there is essentially a linear increase in drag with spoiler deflection for all these configurations. The increase in drag coefficient r
35、anges from about 0.002 to about 0.06. Also for all of these configurations, about 50 percent of the lift loss at a given angle 4 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-of attack occurs at a spoiler deflection of about 15O. Generally, when th
36、e spoilers are deflected, the linear range of the pitching-moment coefficient is extended to a higher angle of attack. The data for the single-spoiler configurations (figs. 6, 7, 8, and 9) indi- cate that, at the maximum spoiler deflection angle of 45O, a nominal lift coeffi- cient of 1.2 can be mai
37、ntained with an increase in angle of attack of less than 1.5O. At the maximum spoiler deflection angle of 45O, the increase in angle of attack to maintain a nominal lift coefficient of 1.2 was about 2.5O for the two-spoiler configurations (figs. 10, 13, 15, and 16), about 3.5O for the three- spoiler
38、 configurations (figs. 11 and 14), and about 4O for the four-spoiler configuration (fig. 12) . At a lift coefficient of 1.2, the maximum increase in drag associated with the spoiler configurations deflected 45O was about 0.03 for the single-spoiler configurations, about 0.04 for the two-spoiler conf
39、igura- tions, about 0.05 for the three-spoiler configurations, and about 0.06 for the four-spoiler configurations. Trailing-Wing Model The maximum rolling-moment coefficient measured by the trailing model and the position of this model relative to the left wing tip of the transport air- craft model
40、are presented in figures 17 to 20 as a function of flight spoiler deflection for the various combinations of flight-spoiler segments investigated. Eleven flight spoiler combinations were investigated and all were effective in reducing the induced rolling moment on the trailing-wing model by as much
41、as 18 to 67 percent. These data were obtained with the trailing-wing model positioned 7.8 transport wing spans behind the transport aircraft model at C,ti = 1.2. The horizontal-tail incidence angle (it), required to trim the transport air- craft model at a lift coefficient of 1.2 (C,ti = 1.2) and th
42、e associated measured drag coefficient are listed in table I1 for the various combinations of flight spoilers. For all of the spoiler configurations investigated, the maximum rolling moment on the trailing-wing model was obtained with the trailing-wing model located inboard of and below the transpor
43、t aircraft model wing tip (figs. 17 to 20). It can be seen in figure 17 that, for any of the single-spoiler configura- tions, the induced rolling moment (C2,m)max on the trailing model decreased with an increase in spoiler deflection angle throughout the spoiler deflection range of Oo to 45O. The gr
44、eatest reduction in (C2,m)max from a single- spoiler configuration (about 48 percent) was realized with spoiler segment 3 at a deflection angle of 450. For all of the two-spoiler configurations (fig. 201, essentially all of the reduction in (CZ,m)max was realized at a spoiler deflection angle of abo
45、ut 300 with the largest reduction in (Cz ,mITax (about 67 percent) being realized for spoiler segments 2 and 4 at a deflectlon angle of 30. For both the three- and four-spoiler configurations (figs. 18 and 19), the reduction in (CZ,) was greater when the spoilers were deflected only 15O. For the thr
46、ee-spoller configurations, the largest reduction in (CZ,) (about 65 percent) was realized with spoiler segments 2, 3, and 4 at a deflec- 5 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-tion angle of 15O. For the four-spoiler configuration, the larg
47、est reduction in (Cz ,TW) (about 53 percent) was realized with the spoiler segments at a deflection angle of 15O. Some of these spoiler combinations at their higher deflection angles could impose unacceptable performance penalties on the air- plane. These penalties include such things as excessive b
48、ody attitude at land- ing, due to the increase in angle of attack required to maintain a given lift coefficient, or an increase in noise, due to the increase in engine thrust required to overcome the drag increase. However, these results show that three combinations of spoiler segments and deflectio
49、ns offer significant trailing- vortex abatement without obviously unacceptable performance penalties. The flight-spoiler configuration of segments 1 and 2, at a deflection angle of 30, which gave a reduction in (C1,m)max of about 46 percent, was shown to be very effective in attenuating the tralling vortex in full-scale flight tests of the jumbo-jet transport air
