The effects of the pressure gradient and surface roughness on turbulent boundary layers have been experimentally investigated. In Part I, smooth- and rough-surface turbulent boundary layers with and without favorable pressure gradients (FPG) are presented. All of the tests have been conducted at the same Reynolds number (based on the length of the flat plate) of 900,000. Streamwise time-mean and fluctuating velocities have been measured using a single-sensor hot-wire probe. For smooth surfaces, the FPG decreases the mean velocity defect and increases the wall shear stress; however, the friction coefficient hardly changes due to the increased freestream velocity. The FPG effect on the streamwise normal Reynolds stress has been examined. The FPG increases the streamwise normal Reynolds stress for y less than 0.6 times the boundary layer thickness. With the zero pressure gradient (ZPG), the roughness increases the mean velocity defect throughout the boundary layer and increases the normal Reynolds stress for y greater than twice the average roughness height. The roughness effect on the mean velocity defect is stronger under the FPG than under the ZPG for y less than 30 times the average roughness height. For y less than 25 times the average roughness height, the roughness effect of increasing normal Reynolds stress is also stronger under the FPG than under the ZPG. Consequently, for a rough surface, the FPG increases the integrated streamwise turbulent kinetic energy, friction coefficient, roughness Reynolds number, and roughness shift. Furthermore, the FPG increases the roughness effects on the integral boundary layer parameters—the boundary layer thickness, momentum thickness, ratio of the displacement thickness to the boundary layer thickness, and shape factor. Thus, the FPG augments the roughness effects on turbulent boundary layers.

References

References
1.
Yun
,
Y. I.
,
Park
,
I. Y.
, and
Song
,
S. J.
,
2005
, “
Performance Degradation Due to Blade Surface Roughness in a Single-Stage Axial Turbine
,”
ASME J. Turbomach.
,
127
, pp.
137
143
.10.1115/1.1811097
2.
Leipold
,
R.
,
Boese
,
M.
, and
Fottner
,
L.
,
2000
, “
The Influence of Technical Surface Roughness Caused by Precision Forging on the Flow Around a Highly Loaded Compressor Cascade
,”
ASME J. Turbomach.
,
122
, pp.
416
424
.10.1115/1.1302286
3.
Acharya
,
M.
,
Bornstein
,
J.
, and
Escudier
,
M. P.
,
1986
, “
Turbulent Boundary Layers on Rough Surfaces
,”
Exp. Fluids
,
4
, pp.
33
47
.10.1007/BF00316784
4.
Brzek
,
B.
,
Cal
,
R. B.
,
Johansson
,
T. G.
, and
Castillo
,
L.
,
2007
, “
Inner and Outer Scalings in Rough Surface Zero Pressure Gradient Turbulent Boundary Layers
,”
Phys. Fluids
,
19
, p.
065101
.10.1063/1.2732439
5.
Furuya
,
Y.
,
Miyata
,
M.
, and
Fujita
,
H.
,
1976
, “
Turbulent Boundary Layer and Flow Resistance on Plates Roughened by Wires
,”
ASME J. Fluids Eng.
,
98
, pp.
635
643
.10.1115/1.3448434
6.
Leonardi
,
S.
,
Orlandi
,
P.
, and
Antonia
,
R. A.
,
2007
, “
Properties of d- and k-Type Roughness in a Turbulent Channel Flow
,”
Phys. Fluids
,
19
, p.
125101
.10.1063/1.2821908
7.
Nikuradse
,
J.
,
1933
, “
Law of Flow in Rough Pipes
,” NACA Technical Memorandum No. 1292, Washington, DC.
8.
Krogstad
,
P. -Å.
,
Antonia
,
R. A.
, and
Browne
,
W. B.
,
1992
, “
Comparison Between Rough- and Smooth-Wall Turbulent Boundary Layers
,”
J. Fluid Mech.
,
245
, pp.
599
617
.10.1017/S0022112092000594
9.
Krogstad
,
P.- Å.
and
Antonia
,
R. A.
,
1999
, “
Surface Roughness Effects in Turbulent Boundary Layers
,”
Exp. Fluids
,
27
, pp.
450
460
.10.1007/s003480050370
10.
Meinders
,
E. R.
and
Hanjalic
,
K.
,
1999
, “
Vortex Structure and Heat Transfer in Turbulent Flow Over a Wall-Mounted Matrix of Cubes
,”
Int. J. Heat Fluid Flow
,
20
, pp.
255
267
.10.1016/S0142-727X(99)00016-8
11.
Djenidi
,
L.
,
Antonia
,
R. A.
,
Amielh
,
M.
, and
Anselmet
,
F.
,
2008
, “
A Turbulent Boundary Layer Over a Two-Dimensional Rough Wall
,”
Exp. Fluids
,
44
, pp.
37
47
.10.1007/s00348-007-0372-5
12.
Joshi
,
P.
,
Liu
,
X.
, and
Katz
,
J.
,
2011
, “
Turbulence in Accelerating Boundary Layers
,”
ASME
-JSME-KSME Joint Fluids Engineering Conference 2011, Hamamatsu, Japan, July 24–29.10.1115/AJK2011-25010
13.
Escudier
,
M. P.
,
Abdel-Hameed
,
A.
,
Johnson
,
M. W.
, and
Sutcliffe
,
C. J.
,
1998
, “
Laminarisation and Re-Transition of a Turbulent Boundary Layer Subjected to Favorable Pressure Gradient
,”
Exp. Fluids
,
25
, pp.
491
502
.10.1007/s003480050255
14.
Herring
,
H. J.
and
Norbury
,
J. F.
,
1967
, “
Some Experiments on Equilibrium Turbulent Boundary Layers in Favorable Pressure Gradients
,”
J. Fluid Mech.
,
27
, pp.
541
549
.10.1017/S0022112067000527
15.
Piomelli
,
U.
,
Balaras
,
E.
, and
Pascarelli
,
A.
,
2000
, “
Turbulent Structures in Accelerating Boundary Layers
,”
J. Turbul.
,
1
, pp.
1
16
.10.1088/1468-5248/1/1/001
16.
Coleman
,
H. W.
,
Moffat
,
R. J.
, and
Kays
,
W. M.
,
1981
, “
Heat Transfer in the Accelerated Fully Rough Turbulent Boundary Layer
,”
ASME J. Heat Transfer
,
103
, pp.
153
158
.10.1115/1.3244411
17.
Chakroun
,
W.,
and
Taylor
,
R. P.
,
1993
, “
The Effect of Moderately Strong Acceleration on Heat Transfer in the Turbulent Rough-Wall Boundary Layer
,”
ASME J. Heat Transfer
,
115
, pp.
782
785
.10.1115/1.2910754
18.
Bons
,
J. P.
, and
McClain
,
S. T.
,
2004
, “
The Effect of Real Turbine Roughness With Pressure Gradient on Heat Transfer
,”
ASME J. Turbomach.
,
126
, pp.
385
394
.10.1115/1.1738120
19.
Coleman
,
H. W.
,
Moffat
,
R. J.
, and
Kays
,
W. M.
,
1977
, “
The Accelerated Fully Rough Turbulent Boundary Layer
,”
J. Fluid Mech.
,
82
, pp.
507
528
.10.1017/S0022112077000810
20.
Cal
,
R. B.
,
Brzek
,
B.
,
Johansson
,
T. G.
, and
Castillo
,
L.
,
2008
, “
Influence of External Conditions on Transitionally Rough Favourable Pressure Gradient Turbulent Boundary Layers
,”
J. Turbul.
,
9
, pp.
1
22
.10.1080/14685240802438346
21.
Cal
,
R. B.
,
Brzek
,
B.
,
Johansson
,
T. G.
, and
Castillo
,
L.
,
2009
, “
The Rough Favourable Pressure Gradient Turbulent Boundary Layer
,”
J. Fluid Mech.
,
641
, pp.
129
155
.10.1017/S0022112009991352
22.
Tay
,
G. F. K.
,
Kuhn
,
D. C. S.
, and
Tachie
,
M. F.
,
2009
, “
Particle Image Velocimetry Study of Rough-Wall Turbulent Flows in Favorable Pressure Gradient
,”
ASME J. Fluids Eng.
,
131
, p.
061205
.10.1115/1.3112389
23.
Launder
,
B. E.,
and
Lockwood
,
F. C.
,
1969
, “
An Aspect of Heat Transfer in Accelerating Turbulent Boundary Layers
,”
ASME J. Heat Transfer
,
91
, pp.
229
234
.10.1115/1.3580132
24.
Schultz
,
M. P.
, and
Flack
,
K. A.
,
2007
, “
The Rough-Wall Turbulent Boundary Layer From the Hydraulically Smooth to the Fully Rough Regime
,”
J. Fluid Mech.
,
580
, pp.
381
405
.10.1017/S0022112007005502
25.
Perry
,
A. E.
, and
Joubert
,
P. N.
,
1963
, “
Rough-Wall Boundary Layers in Adverse Pressure Gradients
,”
J. Fluid Mech.
,
17
, pp.
193
206
.10.1017/S0022112063001245
26.
Nishizawa
,
N.
,
Marusic
, I
.
, and
Perry
,
A. E.
,
1998
, “
Measurement of Wall Shear Stress in Turbulent Boundary Layers Using An Optical Interferometry Method
,” Proceedings of the 13th Australasian Fluid Mechanics Coference, Monash University, Melbourne, Australia.
27.
Madad
,
R.
,
Harun
,
Z.
,
Chauhan
,
K.
,
Monty
,
J. P.
, and
Marusic
,
I.
,
2010
, “
Skin Friction Measurement in Zero and Adverse Pressure Gradient Boundary Layers Using Oil Film Interferometry
,” Proceedings of the 17th Australasian Fluid Mechanics Conference, Auckland, New Zealand.
28.
Jimenez
,
J.
,
2004
, “
Turbulent Flows Over Rough Walls
,”
Annu. Rev. Fluid Mech.
,
36
, pp.
173
196
.10.1146/annurev.fluid.36.050802.122103
29.
Castillo
,
L.
, and
Johansson
,
T. G.
,
2002
, “
The Effects of the Upstream Conditions on a Low Reynolds Number Turbulent Boundary Layer With Zero Pressure Gradient
,”
J. Turbul.
,
3
, pp.
1
19
.10.1088/1468-5248/3/1/031
30.
Ligrani
,
P. M.
, and
Bradshaw
,
P.
,
1987
, “
Spatial Resolution and Measurement of Turbulence in the Viscous Sublayer Using Subminiature Hot-Wire Probes
,”
Exp. Fluids
,
5
, pp.
407
417
.10.1007/BF00264405
31.
Robinson
,
S. K.
,
1991
, “
Coherent Motions in the Turbulent Boundary Layer
,”
Annu. Rev. Fluid Mech.
,
23
, pp.
601
639
.10.1146/annurev.fl.23.010191.003125
32.
Spalart
,
P. R.
, and
Watmuff
,
J. H.
,
1993
, “
Experimental and Numerical Study of a Turbulent Boundary Layer With Pressure Gradient
,”
J. Fluid Mech.
,
249
, pp.
337
371
.10.1017/S002211209300120X
33.
Spalart
,
P. R.
,
1988
, “
Direct Simulation of a Turbulent Boundary Layer up to Reθ=1410
,”
J. Fluid Mech.
,
187
, pp.
61
98
.10.1017/S0022112088000345
34.
Osaka
,
H.
,
Kameda
,
T.
, and
Mochizuki
,
S.
,
1998
, “
Re-Examination of the Reynolds Number-Effects on the Mean Flow Quantities in a Smooth Wall Turbulent Boundary Layer
,”
JSME Int. J., Ser. B
,
41
, pp.
123
-
129
.10.1299/jsmeb.41.123
35.
Raupach
,
M. R.
,
Antonia
,
R. A.
, and
Rjagopalan
,
S.
,
1991
, “
Rough-Wall Turbulent Boundary Layers
,”
ASME Appl. Mech. Rev.
,
44
, pp
1
25
.10.1115/1.3119492
36.
Ryu
,
S.
,
Kim
,
S.
, and
Yoo
,
J. Y.
,
2001
, “
Correlation of Wall Vorticity and Streamwise Velocity Fluctuations in a Turbulent Boundary Layer
,”
Trans. of the KSME B
,
25
, pp.
523
532
.
37.
Moser
,
R. D.,
and
Moin
,
P.
,
1984
, “
Direct Numerical Simulation of Curved Turbulent Channel Flow
,” NASA Technical Memorandum No. 85974, Washington, DC.
38.
Kim
,
J.
,
Moin
,
P.
, and
Moser
,
R.
,
1987
, “
Turbulence Statistics in Fully Developed Channel Flow at Low Reynolds Number
,”
J. Fluid Mech.
,
177
, pp.
133
166
.10.1017/S0022112087000892
39.
Purtell
,
L. P.
,
Klebanoff
,
P. S.
, and
Buchley
,
F. T.
,
1981
, “
Turbulent Boundary Layer at Low Reynolds Number
,”
Phys. Fluids
,
24
, pp.
802
811
.10.1063/1.863452
40.
Achenbach
,
E.
,
1971
, “
Influence of Surface Roughness on the Cross-Flow Around a Circular Cylinder
,”
J. Fluid Mech.
,
46
, pp.
321
335
.10.1017/S0022112071000569
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