The aerodynamic properties and flowfield of a NACA 0015 airfoil over a wavy ground were investigated experimentally via surface pressure and particle image velocimetry (PIV) measurements. Flat-surface results were also obtained to be served as a comparison. For the wavy ground, there exhibited a cyclic variation in the sectional lift coefficient Cl over an entire wavelength. The maximum Cl observed at the wave peak (produced by the wavy ground-induced RAM pressure) and minimum Cl occurred at the wave valley (resulting from the unusual suction pressure developed on the airfoil's lower surface due to the converging-diverging flow passage developed underneath it) reduced with increasing ground distance. By contrast, the pitching-moment coefficient showed an opposite trend to the variation in Cl and had an almost all-negative value. Meanwhile, two peak values in the drag coefficient over each wavelength were observed. The wavy ground effect-produced gains in the mean Cl and lift-to-drag ratio were at the expense of longitudinal stability. Additional measurements considering different wavelengths and amplitudes are needed to further quantify the impact of wavy ground on wing-in-ground effect (WIG) airfoils and wings.

References

1.
Steinbach
,
D.
,
1997
, “
Aerodynamic Characteristics of a Two-Dimensional Airfoil With Ground Effects
,”
J. Aircr.
,
34
(
3
), pp.
455
456
.
2.
Divitiis
,
N. D.
,
2005
, “
Performance and Stability of a Winged Vehicle in Ground Effect
,”
J. Aircr.
,
42
(
1
), pp.
148
157
.
3.
Angle
,
E. M.
,
Brian
,
O. M.
,
Franz
,
A. P.
, and
Smith
,
J. E.
,
2009
, “
Pitch Stability Analysis of an Airfoil in Ground Effect
,”
J. Aircr.
,
46
(
3
), pp.
756
762
.
4.
Wang
,
H.
,
Teo
,
C. J.
,
Khoo
,
B. C.
, and
Goh
,
C. J.
,
2013
, “
Computational Aerodynamics and Flight Stability of Wing-in-Ground (WIG) Craft
,”
Procedia Eng.
,
67
, pp.
15
24
.
5.
Tomaru
,
H.
, and
Kohama
,
Y.
,
1990
, “
Experiments on Wing in Ground Effect With Fixed Ground Plates
,”
Second KSME-JSME Fluids Engineering Conference
, Seoul, South Korea, Oct. 10–13, pp.
370
373
.http://www.dbpia.co.kr/Journal/ArticleDetail/NODE00326836
6.
Hsiun
,
C. M.
, and
Chen
,
C. K.
,
1996
, “
Aerodynamic Characteristics of a Two-Dimensional Airfoil With Ground Effect
,”
J. Aircr.
,
33
(
2
), pp.
386
392
.
7.
Zerihan
,
J.
, and
Zhang
,
X.
,
2000
, “
Aerodynamics of a Single-Element Wing in Ground Effect
,”
J. Aircr.
,
37
(
6
), pp.
1058
1064
.
8.
Moore
,
N.
,
Wilson
,
P. A.
, and
Peters
,
A. J.
,
2000
, “
An Investigation Into Wing in Ground Effect Airfoil Geometry
,”
RTO SCI Symposium on Challenges in Dynamics, System Identification, Control and Handling Qualities for Land, Air, Sea and Space Vehicles
, Berlin, May 13–15, Paper No.
RTO-MP-095
.https://eprints.soton.ac.uk/51083/1/51083.pdf
9.
Mahon
,
S.
, and
Zhang
,
X.
,
2005
, “
Computational Analysis of Pressure and Wake Characteristics of an Aerofoil in Ground Effect
,”
ASME J. Fluids Eng.
,
127
(
2
), pp.
290
298
.
10.
Ahmed
,
M. R.
,
Takasaki
,
T.
, and
Kohama
,
Y.
,
2007
, “
Aerodynamics of a NACA 4412 Airfoil in Ground Effect
,”
AIAA J.
,
45
(
1
), pp.
37
47
.
11.
Luo
,
S. C.
, and
Chen
,
Y. S.
,
2012
, “
Ground Effect on Flow Past a Wing With a NACA 0015 Cross-Section
,”
Exp. Therm. Fluid Sci.
,
40
, pp.
18
28
.
12.
Lee
,
T.
,
Majeed
,
A.
,
Siddiqui
,
B.
, and
Tremblay-Dionne
,
V.
,
2017
, “
Impact of Ground Proximity on the Aerodynamic Properties of an Unsteady Airfoil
,”
J Aerosp. Eng.
, epub.
13.
Rozhdestvensky
,
K. V.
,
2006
, “
Wing-in-Ground Effect Vehicles
,”
Prog. Aerosp. Sci.
,
42
(
3
), pp.
211
283
.
14.
Ando
,
S.
,
Sakai
,
T.
, and
Nitta
,
K.
,
1992
, “
Analysis of Motion of Airfoil Flying Over Wavy-Wall Surface
,”
Jpn. Soc. Aeronaut. Space Sci. Trans.
,
35
(
107
), pp.
27
38
.
15.
Morishita
,
E.
, and
Ashihara
,
K.
,
1995
, “
Ground Effect Calculation of a Two-Dimensional Airfoil Over a Wavy Surface
,”
Jpn. Soc. Aeronaut. Space Sci.
,
38
(
119
), pp.
77
90
.
16.
Im
,
Y.-H.
, and
Chang
,
K.-S.
,
2000
, “
Unsteady Aerodynamics of a Wing-in-Ground-Effect Airfoil Flying Over a Wavy Wall
,”
J. Aircr.
,
37
(
4
), pp.
690
696
.
17.
Rozhdestvensky
,
K. V.
,
2000
,
Aerodynamics of a Lifting System in Extreme Ground Effect
,
Springer
,
Berlin
.
18.
Benedict
,
K.
,
Kornev
,
N. V.
,
Meyer
,
M.
, and
Ebert
,
J.
,
2002
, “
Complex Mathematical Model of the WIG Motion Including the Take-Off Mode
,”
Ocean Eng.
,
29
(
3
), pp.
315
357
.
19.
Matveev
,
K. I.
,
2012
, “
Heave-Pitch Motions of a Platform Flying in Extreme Ground Effect
,”
J. Aerosp. Eng.
,
25
(
2
), pp.
238
245
.
20.
Matveev
,
K. I.
,
2015
, “
Heave and Pitch Motions of Wing-in-Ground Craft Flying Above Wavy Surface
,”
Front. Aerosp. Eng.
,
4
(
2
), pp.
43
47
.
21.
Qu
,
Q.
,
Jia
,
X.
,
Wang
,
W.
,
Liu
,
P.
, and
Agarwal
,
R. K.
,
2014
, “
Numerical Study of the Aerodynamics of a NACA 4412 Airfoil in Dynamic Ground Effect
,”
Aerosp. Sci. Technol.
,
38
, pp.
56
63
.
22.
Lee
,
T.
,
2016
, “
Impact of Gurney Flaplike Strips on the Aerodynamic and Vortex Flow Characteristics of a Reverse Delta Wing
,”
ASME J. Fluids Eng.
,
138
(
6
), p.
061104
.
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