1、NASA CONTRACTOR REPORT ;+-I EFFECTIVENESS OF SPOILERS ON THE GA(W)-1 AIRFOIL WITH A HIGH PERFORMANCE FOWLER FLAP ij. Prepared by WICHITA STATE UNITE Wichita, Kans. 67208 for Langley Research Center NATIONAL AERONAUTICS AND SPACE ADMINISTRATION l WASHINGTON, D. c. . -(-hy -N75 - - Provided by IHSNot
2、for ResaleNo reproduction or networking permitted without license from IHS-,-,-TECH LIBRARY KAFB, NM llnlllnmirrllllllIlllllllllm OOb3240 1. Report No. 2. Government Accession No. NASA CR-2538 4. Title and Subtitle EFFECTIVENESS OF SPOILERS ON THE GA(W)-1 AIRFOIL WITH A HIGH PERFORMANCE FOWLER FLAP
3、7. Author(s) W. H, Wentz, Jr. 9. Performing Organization Name and Address Wichita State University Wichita, Kansas 67208 ;2. Sponsoring Agency Name and Address 3. Recipients Catalog No. 5. Report Data my 1975 6. Performing Organization Coda 8. Performing Organization Report No. 10. Work Unit No. 505
4、-10-11-03 11. Contract or Grant No. NGR-17-002-072 13. Type of Report and Period Covered Contractor Report National Aeronautics and Space Administration Washington, DC 20546 15. Supplementary Notes 14. Sponsoring Agency Code 505-10-11-03 Prepared by Wichita State University for the University of Kan
5、sas. Topical Report. 16. Abstract Two-dimensional wind-tunnel tests have been conducted at a Reynolds number of 2 X lo6 to determine effectiveness of spoilers applied to the GA(W)-1 airfoil. Tests of several spoiler configurations show adequate control effectiveness with flap nested. With 40 flap, m
6、any spoiler configurations result in negative control response for small deflections, followed by highly non-linear control response at higher deflections, including substantial aerodynamic hysteresis for several configurations. It was found that providing a vent path allowing lower surface air to e
7、scape to the upper surface as the spoiler opens alleviates control reversal and hysteresis tendencies. Spoiler cross-sectional shape variations generally had modest influence on control characteristics. A series of comparative tests of vortex generators applied to the (GA-W)-1 airfoi show that trian
8、gular planform vortex generators are superior to square planform vortex generators of the same span. 17. Kay Words (Suggested by Author(s) 18. Distribution Statement Spoilers, with Fowler flaps, two dimensions Variation of spoiler section Unclassified - Unlimited Spoilers with leading edge gap Trian
9、gular vortex generators Subject Category 02 Aerodynamics 16. Security Ciassif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages 22. Price Unclassified Unclassified 68 $4.25 *For sale by the frlational Technical Information Service, Springfield, Virginia 22151 Provided by IHSNot
10、 for ResaleNo reproduction or networking permitted without license from IHS-,-,-SUMMARY Two-dimensional wind tunnel tests have been conducted to determine effectiveness of spoilers applied to the GA(W)-1 airfoil. Tests of several spoiler configurations show adequate control effectiveness with flap n
11、ested. With 40. flap, many spoiler configurations result in negative control response for small deflections, followed by highly non-linear control response at higher deflections, including substantial aero- dynamic hysteresis for several configurations. It was found that a properly designed vent pat
12、h allowing lower surface air to escape to the upper surface as the spoiler opens alleviates control reversal and hysteresis tendencies. The spoiler non-linear control characteristics observed in the present tests are quite similar to characteristics reported by earlier researchers for airfoils with
13、high-lift coefficient Fowler flaps. Several of the vented spoiler con- figurations tested exhibit positive, monotonic control character- istics for all control deflections and angles of attack, flaps nested or extended. Spoiler cross-sectional shape variations generally had modest influence on contr
14、ol characteristics. It is recommended that reflection plane tests be carried out to evaluate three- dimensional aerodynamic effects on hysteresis, and to determine factors whichinfluence spoiler hinge moments. A series of comparative tests of vortex generators applied to the GA(W)-1 airfoil show tha
15、t triangular planform vortex generators are superior to square planform vortex generators of the same span, in providing increased cRmax with minimum drag penalty. I: Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Introduction The present research i
16、s one component of NASA Langley Research Center sponsored activities particularly aimed,at providing advanced aeronautical technology to general aviation., The research reported here was undertaken to deve1op.a spoiler lateral control system for application to a high performance low speed airfoil (G
17、A(W)-1) with a large Fowler flap. The project was undertaken in support of an Advanced Technology Light Twin (ATLIT) aircraft, a research vehicle designed to demonstrate advanced technology concepts. The ATLIT airplane (Ref. 1) features a spoiler only lateral control system to permit full-span flaps
18、 for high landing and takeoff performance. The research thus developed, of course, has potential applic- ability to any flight vehicle designed to operate at low Mach numbers. Two-dimensional airfoil and flap aerodynamic character- istics have been reported earlier (Refs. 2, 3, 4). The present repor
19、t presents results of wind tunnel tests of more than twenty spoiler configurations applied to the GA(W)-1 airfoil. Symbols The force and moment data have been referred to the .25c location on the flap-nested airfoil. Dimensional quantities are given in both International (SI) Units and U. S. Customa
20、ry Units. Measurements were made in U. S. Customary Units. Conversion factors between the various units may be found in Reference 5. The symbols used in the present report are defined as follows: C airfoil reference chord (flap nested) 5 airfoil section lift coefficient, section lift/(dynamic pressu
21、re x chord). cd airfoil section drag coefficient, section drag/(dynamic pressure x chord). rn airfoil section pitching moment coefficient with respect to the .25c location, section moment/(dynamic pressure x chord2). 2 Provided by IHSNot for ResaleNo reproduction or networking permitted without lice
22、nse from IHS-,-,-I - cP coefficient of pressure, (P-Pm)/dynamic pressure. a angle of attack, degrees A increment 6 rotation of surface from nested position, degrees Subscripts S Spoiler EXPERIMENTAL INVESTIGATIONS Wind Tunnel Models and Instrumentation All tests were conducted using the GA(W)-1 airf
23、oil with a 30% Fowler flap. Airfoil and flap geometry are shown in Figure 1. Testing was conducted in the WSU 2.13m x 3.05m (7 x 10) Low Speed tunnel, fitted with inserts to provide a 2.13 m x 0.91m (7 x 3) two-dimensional working section. Details of the model installation are given in Reference 2.
24、Early spoiler tests were conducted utilizing spoilers fabricated from 1.80 mm (.071“) flat aluminum sheet stock supported by sets of 4 wedge-type mounting blocks 6.35 mm (.25“) wide to provide the various spoiler deflections, as shown in Figure 2(a). The spoiler assemblies were retained by cloth adh
25、esive tape applied along the spoiler leading edges and along the trailing edge of the wedge blocks. After these early tests indicated the need for venting of air from lower to upper surface, the wing aft section was modified as shown in Figure 2(b). This model utilizes a 15% trailing edge section mo
26、unted on 4 spanwise ribs. The spoilers are attached to hinged sectors located at the 70% chord location at each rib station. Spoiler deflections are obtained by rotating the sector and spoiler plate relative to the ribs. A small screw retains each sector at the proper deflection angle. Spoiler defle
27、ction angles from O“ to 60 are easily obtained with this setup. Various spoiler plates, internal flow fillers and fair- ings were fabricated and tested. Test Reynolds number was 2.3 x 3 106 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Three-compon
28、ent force measurements were obtained on all configurations utilizing the tunnel pyramidal balance system. The experimental setup utilizes large disk end plates which are attached directly to the wing spar. As a consequence, a fairly large drag dynamic tare is measured by the balance system. This tar
29、e drag has been determined by wake rake air- foil section drag measurements as reported in Reference 2. All data have been corrected for this effect as well as for the wind tunnel wall effects, as outlined in Reference 6. For the purposes of the present tests, a special data reduction computer progr
30、am was written to calculate directly the incremental effects of spoiler deflections. Thus most of the data is presented in the form of increments utilizing zero spoiler deflection as a base line. In certain instances, however, conventional cR versus a plots are presented to illus- trate non-linear c
31、haracteristics observed during these tests. Spoiler Tests The first series of spoiler tests were carried out with simple flat plate spoilers attached to the upper surface of the GA(W)-1 airfoil. These tests were carried out with the following configurations: Table 1 - Flat Plate Spoiler Configuratio
32、ns Angle of Attack Chords Deflections Hingelines -5O to +20 7.5% and 15% 20, 40, 60 60% and 70% From this series of runs it was found that certain combin- ations of negative angle of attack and 40 flap resulted in zero change in lift coefficient with 20 spoiler deflection (zero control). With flap n
33、ested, on the other hand, no control problems were encountered. These results have been reported in Reference 2. Based upon these results, the present detailed studies of smaller spoiler deflections were carried out. 4 Provided by IHSNot for ResaleNo reproduction or networking permitted without lice
34、nse from IHS-,-,-Figure 3 illustrates the performance of a simple 15% chord spoiler with hingeline at 70% and 85% chord. For the flap nested case, spoiler control is nearly linear, except for a “softening“ or dead-band tendency for small deflections at high angles of attack. These tendencies, not un
35、like ailer- on control near stall, would probably be quite acceptable. With 40“ flap deflection and 70% hingeline, on the other hand, the present tests illustrate (Fig. 4) not only zero control for small deflections, but actually show regions of control reversal. Comparison of these data with spoile
36、r control forces from reflection plane tests reported in Reference 7 reveals that the same characteristic trends are also present for other airfoils with large Fowler flaps. Tuft studies of the upper surface flow with small spoiler deflections revealed that the flow was separating aft of the spoiler
37、, but the flap was fully attached, even for spoiler deflections of loo. This is not too surprising when it is realized that the projection heights of the spoiler trailing edge are much smaller than the flap slot gap. Under these conditions the spoiler evidently has the effect of adding a small amoun
38、t of positive camber to the airfoil section. Since the Kutta condition is preserved by attached flow at the flap trailing edge, a positive increment in lift (negative spoiler control) results. The “added camber“ theory is supported by the pitching moment data which show a nose-down tendency for smal
39、l spoiler deflections. The data in Figure 5 show that the addition of a 1.5% leading edge gap to the spoiler has no significant effect for spoiler deflections of 15O and greater. Data from Reference 7 indicate that providing lower surface ventilation air through the. spoiler cavity will improve cont
40、rol effectiveness at small deflections. To determine whether venti- lation would help spoiler control at small deflections, a series 5 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-of holes were bored through the model to crudely provide partial ve
41、ntilation. Results of this test indicated that the control reversal could be eliminated. The model was then modified as shown in Figure 2(b). The entire aft 30% of the wing was removed and a new trailing section was fabricated, with four ribs for structural support, sectors for positive spoiler posi
42、tion, and hinge-points at the 70% chord station at each rib. With the modified model geometry, it was possible to shim the 15% chord trailing edge segment and obtain a series of spoiler effectiveness data for a “slot-lip“ type spoiler (Figure 6). These data show positive control even for control sur
43、face deflections as small as 5O. Evidently opening the flap slot serves as a powerful lift regulating mechanism. The problem of designs utilizing the slot lip spoiler is the large hinge moment associated with zero spoiler deflection, flaps down. The magnitude of this moment can be calculated from th
44、e pressure dis- tribution data of Reference 2, which show AC P values of 2.0 for 40 flap deflection. Tests of a 15% chord spoiler with lower surface venting revealed that positive control could be provided at small spoiler deflections. At moderate deflections, however, it was discovered that a serio
45、us aerodynamic hysteresis problem was present. Figure 7 illustrates this effect: for fixed spoiler and flap settings, two distinct cR versus a curves are produced, differing in lift coefficient by about 0.4. The hysteresis band persists from -15 to +6O angle of attack. A small half dowel was fitted
46、into the cavity in an attempt to relieve the hysteresis effect. It is seen that this modification eliminated the hystere- sis for 15O spoiler deflection. For 20 spoiler deflection a narrow hysteresis band is observed, even with the cavity nose dowel in place (Figure 8). 6 .- . _ . I I 111 Provided b
47、y IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-The significant favorable benefits of lower surface venting are clearly illustrated by comparing Figure 8 with Figure 4. It is seen that the tendency for control reversal at low spoiler deflections has been elimi
48、nated. While the control effectiveness curves are highly non-linear, positive control response is provided throughout the angle of attack and spoiler deflection ranges. Effects of a 4% spoiler leading edge gap are shown in Figure 9. Effects of Spoiler Chord Effects of spoiler chord variations are il
49、lustrated by comparing Figures 8, 10 and 11 which show spoiler effectiveness for 15%, 7.5% and 10% spoiler chords, respectively. These data illustrate very similar characteristics when compared at the same A h/c rather than at the same 6s. Thus the data illustrate that spoiler performance is much more strongly dependent upon maximum proj
