The effects of sweep-back angle (Λ), Reynolds number (Re), and angle of attack (α) on the boundary-layer flow structures and aerodynamic performance of a finite swept-back wing were experimentally investigated. The Reynolds number and sweep-back angle used in this test is 30,000<Re<130,000 and 0degΛ45deg. The wing model was made of stainless steel, and the wing airfoil is NACA 0012. The chord length is 6 cm, and the semiwing span is 30 cm; and therefore, the semiwing aspect ratio is 5. The boundary-layer flow structures were visualized using the surface oil-flow technique. Seven boundary-layer flow modes were categorized by changing Re and α. A six-component balance is used to determine aerodynamic loadings. The aerodynamic performance is closely related to the boundary-layer flow modes. The stall angle of attack (αstall) is deferred from 9 deg to 10 deg (for an unswept wing), to 30 deg to 35 deg (for a swept-back wings of Λ>30deg). The deferment of αstall is induced from the increased rotation energy and turbulent intensity generated from the secondary flow. Furthermore, the increased rotation energy and turbulent intensity resisted the reverse pressure generated at high α.

1.
Clancy
,
L. J.
, 1975,
Aerodynamics
,
Wiley
,
New York
, pp.
72
73
.
2.
Lissaman
,
P. B. S.
, 1983, “
Low Reynolds Number Airfoils
,”
Annu. Rev. Fluid Mech.
0066-4189,
15
, pp.
223
239
.
3.
Crabtree
,
L. F.
, 1957, “
Effects of Leading-Edge Separation on Thin Wings in Two-Dimensional Incompressible Flow
,”
J. Aeronaut. Sci.
0095-9812,
24
(
8
), pp.
597
604
.
4.
Ward
,
J. R.
, 1963, “
The Behavior and Effects of Laminar Separation Bubbles on Airfoils in Incompressible Flow
,”
J. R. Aeronaut. Soc.
0368-3931,
67
(
12
), pp.
783
790
.
5.
Arena
,
A. V.
, and
Mueller
,
T. J.
, 1980, “
Laminar Separation, Transition, and Turbulent Reattachment Near the Leading Edge of Airfoils
,”
AIAA J.
0001-1452,
18
(
7
), pp.
747
753
.
6.
Katz
,
J.
, 1999, “
Wing/Vortex Interactions and Wing Rock
,”
Prog. Aerosp. Sci.
0376-0421,
35
(
7
), pp.
727
750
.
7.
Mueller
,
T. J.
, and
Batill
,
S. M.
, 1982, “
Experimental Studies of Separation on a Two-Dimensional Airfoil at Low Reynolds Numbers
,”
AIAA J.
0001-1452,
20
(
4
), pp.
457
463
.
8.
Pohlen
,
L. J.
, and
Mueller
,
T. J.
, 1984, “
Boundary Layer Characteristics of the Miley Airfoil at Low Reynolds Numbers
,”
J. Aircr.
0021-8669,
21
(
9
), pp.
658
664
.
9.
Hsiao
,
F. -B.
,
Liu
,
C. -F.
, and
Tang
,
Z.
, 1989, “
Aerodynamic Performance and Flow Structure Studies of a Low Reynolds Number Airfoil
,”
AIAA J.
0001-1452,
27
(
2
), pp.
129
137
.
10.
Purser
,
P. E.
, and
Spearman
,
M. L.
, 1951, “
Wind-Tunnel Tests at Low Speed of and Yawed Wings Having Various Plane Forms
,” NACA Technical Paper No. 2445.
11.
Black
,
J.
, 1956, “
Flow Studies of the Leading Edge Stall on a Swept-Back Wing at High Incidence
,”
J. R. Aeronaut. Soc.
0368-3931,
60
, pp.
51
60
.
12.
Squire
,
L. C.
, 1961, “
The Motion of a Thin Oil Sheet Under the Steady Boundary Layer on a Body
,”
J. Fluid Mech.
0022-1120,
11
(
2
), pp.
161
179
.
13.
Poll
,
D. I. A.
, 1986, “
Spiral Vortex Flow Over a Swept-Back Wing
,”
Aeronaut. J.
0001-9240,
90
(
895
), pp.
185
199
.
14.
Mueller
,
T. J.
,
Pohlen
,
L. J.
,
Conigliaro
,
P. E.
, and
Jansen
,
B. J.
, 1983, “
The Influence of Free-Stream Dimensional on Low Reynolds Number Airfoil Experiments
,”
Exp. Fluids
0723-4864,
1
, pp.
3
14
.
15.
Mueller
,
T. J.
, 1985, “
The Influence of Laminar Separation and Transition on the Low Reynolds Number Airfoil Hysteresis
,”
J. Aircr.
0021-8669,
22
(
9
), pp.
763
770
.
16.
Liu
,
M. J.
,
,
Z. Y.
,
Qiu
,
C. H.
,
Su
,
W. H.
,
Gao
,
X. K.
,
Deng
,
X. Y.
, and
Xiong
,
S. W.
, 1980, “
Flow Patterns and Aerodynamics Characteristic of a Wing-Strake Configuration
,”
J. Aircr.
0021-8669,
17
(
5
), pp.
332
338
.
17.
Huang
,
R. F.
,
Shy
,
W. W.
,
Lin
,
S. W.
, and
Hsiao
,
F. -B.
, 1996, “
Influence of Surface Flow on Aerodynamic Loads of a Cantilever Wing
,”
AIAA J.
0001-1452,
34
(
3
), pp.
527
532
.
18.
Yen
,
S. C.
, and
Hsu
,
C. M.
, 2007, “
Influence of Boundary Layer Behavior on Aerodynamic Coefficients of a Swept-Back Wing
,”
ASME J. Fluids Eng.
0098-2202,
129
(
6
), pp.
674
681
.
19.
Shames
,
I. H.
, 1992,
Mechanics of Fluid
,
3rd ed.
,
McGraw-Hill
,
Singapore
, p.
632
.
20.
Abbott
,
I. H.
, and
Von Doenhoff
,
A. E.
, 1959,
Theory of Wing Section
,
Dover
,
New York
, pp.
113
115
.
21.
Merzkirch
,
W.
, 1974,
Flow Visualization
,
Academic
,
New York
, pp.
53
56
.
22.
Bertin
,
J. J.
, and
Smith
,
M. L.
, 1989,
Aerodynamics for Engineers
,
2nd ed.
,
Prentice-Hall
,
Englewood Cliffs, NJ
, pp.
204
213
and pp.
235
257
.
23.
Hoerner
,
S. F.
, and
Borst
,
H. V.
, 1975,
Fluid Dynamic Lift
, published by
Mrs. Liselotte A. Hoerner
,
Brick Town, NJ
, pp.
4.22
4.23
and
15.6
15.8
.
24.
Huang
,
R. F.
, and
Lee
,
H. W.
, 1999, “
Effect of Freestream Turbulence on Wing-Surface Flow and Aerodynamics Performance
,”
AIAA J.
0001-1452,
36
(
6
), pp.
965
972
.
25.
Schewe
,
G.
, 2001, “
Reynolds-Number Effects in Flow Around More-or-Less Bluff Bodies
,”
J. Wind. Eng. Ind. Aerodyn.
0167-6105,
89
(
14-15
), pp.
1267
1289
.
This content is only available via PDF.
You do not currently have access to this content.