Experimental results from a channel with shallow dimples placed on one wall are given for Reynolds numbers based on channel height from 3,700 to 20,000, levels of longitudinal turbulence intensity from 3% to 11% (at the entrance of the channel test section), and a ratio of air inlet stagnation temperature to surface temperature of approximately 0.94. The ratio of dimple depth to dimple print diameter δD is 0.1, and the ratio of channel height to dimple print diameter HD is 1.00. The data presented include friction factors, local Nusselt numbers, spatially averaged Nusselt numbers, a number of time-averaged flow structural characteristics, flow visualization results, and spectra of longitudinal velocity fluctuations which, at a Reynolds number of 20,000, show a primary vortex shedding frequency of 8.0Hz and a dimple edge vortex pair oscillation frequency of approximately 6.5Hz. The local flow structure shows some qualitative similarity to characteristics measured with deeper dimples (δD of 0.2 and 0.3), with smaller quantitative changes from the dimples as δD decreases. A similar conclusion is reached regarding qualitative and quantitative variations of local Nusselt number ratio data, which show that the highest local values are present within the downstream portions of dimples, as well as near dimple spanwise and downstream edges. Local and spatially averaged Nusselt number ratios sometimes change by small amounts as the channel inlet turbulence intensity level is altered, whereas friction factor ratios increase somewhat at the channel inlet turbulence intensity level increases. These changes to local Nusselt number data (with changing turbulence intensity level) are present at the same locations where the vortex pairs appear to originate, where they have the greatest influences on local flow and heat transfer behavior.

1.
Mahmood
,
G. I.
,
Hill
,
M. L.
,
Nelson
,
D. L.
,
Ligrani
,
P. M.
,
Moon
,
H.-K.
, and
Glezer
B.
, 2001, “
Local Heat Transfer and Flow Structure On and Above a Dimpled Surface in a Channel
,”
ASME J. Turbomach.
0889-504X,
123
, No.
1
, pp.
115
123
.
2.
Burgess
,
N. K.
,
Oliveira
,
M. M.
, and
Ligrani
,
P. M.
, 2003, “
Nusselt Number Behavior on Deep Dimpled Surfaces Within a Channel
,”
ASME J. Heat Transfer
0022-1481,
125
, No.
1
, pp.
11
18
.
3.
Mahmood
,
G. I.
, and
Ligrani
,
P. M.
, 2002, “
Heat Transfer in a Dimpled Channel: Combined Influences of Aspect Ratio, Temperature Ratio, Reynolds Number, and Flow Structure
,”
Int. J. Heat Mass Transfer
0017-9310,
45
, No.
10
, pp.
2011
2020
.
4.
Mahmood
,
G. I.
,
Sabbagh
,
M. Z.
, and
Ligrani
,
P. M.
, 2001, “
Heat Transfer in a Channel With Dimples and Protrusions on Opposite Walls
,”
AIAA J. Thermophys. Heat Transfer
,
15
, No.
3
, pp.
275
283
.
5.
Ligrani
,
P. M.
,
Mahmood
,
G. I.
,
Harrison
,
J. L.
,
Clayton
,
C. M.
, and
Nelson
,
D. L.
, 2001, “
Flow Structure and Local Nusselt Number Variations in a Channel With Dimples and Protrusions on Opposite Walls
,”
Int. J. Heat Mass Transfer
0017-9310,
44
, No.
23
, pp.
4413
4425
.
6.
Afanasyev
,
V. N.
,
Chudnovsky
,
Y. P.
,
Leontiev
,
A. I.
, and
Roganov
,
P. S.
, 1993, “
Turbulent Flow Friction and Heat Transfer Characteristics for Spherical Cavities on a Flat Plate
,”
Exp. Therm. Fluid Sci.
0894-1777,
7
, pp.
1
8
.
7.
Belen’kiy
,
M. Y.
,
Gotovskiy
,
M. A.
,
Lekakh
,
B. M.
,
Fokin
,
B. S.
, and
Dolgushin
,
K. S.
, 1994, “
Heat Transfer Augmentation Using Surfaces Formed by a System of Spherical Cavities
,”
Heat Transfer Res.
,
25
, No.
2
, pp.
196
203
.
8.
Kesarev
,
V. S.
, and
Kozlov
,
A. P.
, 1994, “
Convective Heat Transfer in Turbulized Flow Past a Hemispherical Cavity
,”
Heat Transfer Res.
,
25
, No.
2
, pp.
156
160
.
9.
Terekhov
,
V. I.
,
Kalinina
,
S. V.
, and
Mshvidobadze
,
Y. M.
, 1995, “
Flow Structure and Heat Transfer on a Surface With a Unit Hole Depression
,”
Russ. J. Eng. Thermophys.
1051-8053,
5
, pp.
11
33
.
10.
Schukin
,
A. V.
,
Koslov
,
A. P.
, and
Agachev
,
R. S.
, 1995, ‘
study and Application of Hemispherical Cavities For Surface Heat Transfer Augmentation
,” ASME Paper No. 95-GT-59,
ASME 40th International Gas Turbine and Aeroengine Congress and Exposition
,
Houston
, Texas.
11.
Gortyshov
,
Y. F.
,
Popov
,
I. A.
,
Amirkhanov
,
R. D.
, and
Gulitsky
,
K. E.
, 1998, “
studies of Hydrodynamics and Heat Exchange in Channels With Various Types of Intensifiers
,”
Proceedings of 11th International Heat Transfer Congress
,
6
, pp.
83
88
.
12.
Chyu
,
M. K.
,
Yu
,
Y.
,
Ding
H.
,
Downs
,
J. P.
, and
Soechting
,
F. O.
, 1997, “
Concavity Enhanced Heat Transfer in an Internal Cooling Passage
,” ASME Paper No. 97-GT-437,
ASME 42nd International Gas Turbine and Aeroengine Congress and Exposition
,
Orlando
, Florida.
13.
Lin
,
Y.-L.
,
Shih
,
T. I.-P.
, and
Chyu
,
M. K.
, 1999, “
Computations of Flow and Heat Transfer in a Channel With Rows of Hemispherical Cavities
,” ASME Paper No. 99-GT-263,
ASME 44th International Gas Turbine and Aeroengine Congress and Exposition
,
Indianapolis
, Indiana.
14.
Moon
,
H.-K.
,
O’Connell
,
T.
, and
Glezer
,
B.
, 1999, “
Channel Height Effect on Heat Transfer and Friction in a Dimpled Passage
,” ASME Paper No. 99-GT-163,
ASME 44th International Gas Turbine and Aeroengine Congress and Exposition
,
Indianapolis
, Indiana.
15.
Terekhov
,
V. I.
, and
Kalinina
,
S. V.
, 2002, “
Flow and Heat Transfer in a Single Spherical Cavity: State of the Problem and Unanswered Questions (Review)
,”
Thermophysics and Aeromechanics
,
9
, No.
4
, pp.
475
496
.
16.
Isaev
,
S. A.
,
Leontiev
,
A. I.
,
Kudryavtsev
,
N. A.
, and
Pushnyi
,
I. A.
, 2003, “
The Effect of Rearrangement of the Vortex Structure on Heat Transfer Under Conditions of Increasing Depth of a Spherical Dimple in the Wall of a Narrow Channel
,”
Teplofiz. Vys. Temp.
0040-3644,
41
, No.
2
, pp.
268
272
.
17.
Ligrani
,
P. M.
,
Harrison
,
J. L.
,
Mahmood
,
G. I.
, and
Hill
,
M. L.
, 2001, “
Flow Structure Due to Dimple Depressions on a Channel Surface
,”
Phys. Fluids
1070-6631,
13
, No.
11
, pp.
3442
3451
.
18.
Ligrani
,
P. M.
,
Singer
,
B. A.
, and
Baun
,
L. R.
, 1989, “
Miniature Five-Hole Pressure Probe for Measurement of Three Mean Velocity Components in Low Speed Flow
,”
J. Phys. E
0022-3735,
22
, No.
10
, pp.
868
876
.
19.
Ligrani
,
P. M.
,
Singer
,
B. A.
, and
Baun
,
L. R.
, 1989, “
Spatial Resolution and Downwash Velocity Corrections for Multiple-Hole Pressure Probes in Complex Flows
,”
Exp. Fluids
0723-4864,
7
, No.
6
, pp.
424
426
.
20.
Ligrani
,
P. M.
, 2000, “
Flow Visualization and Flow Tracking as Applied to Turbine Components in Gas Turbine Engines
,”
Meas. Sci. Technol.
0957-0233,
11
, No.
7
, pp.
992
1006
.
21.
Kline
,
S. J.
and
McClintock
,
F. A.
, 1953, “
Describing Uncertainties in Single Sample Experiments
,”
Mech. Eng. (Am. Soc. Mech. Eng.)
0025-6501,
75
, pp.
3
8
.
22.
Moffat
,
R. J.
, 1988, “
Describing the Uncertainties in Experimental Results,
Exp. Therm. Fluid Sci.
0894-1777,
1
, No.
1
, pp.
3
17
.
23.
Lienhard
,
J. H.
, 1987,
A Heat Transfer Textbook
,
2nd ed.
,
Prentice-Hall Inc.
, Englewood Cliffs, New Jersey, pp.
338
343
.
24.
Ligrani
,
P. M.
,
Oliveira
,
M. M.
, and
Blaskovich
,
T.
, 2003, “
Comparison of Heat Transfer Augmentation Techniques
,”
AIAA J.
0001-1452,
41
, No.
3
, pp.
337
362
.
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