Cooling channels, roughened with repeated ribs, are commonly employed as a means of cooling turbine blades. The increased level of mixing induced by these ribs enhances the convective heat transfer in the blade cooling cavities. Many previous investigations have focused on the heat transfer coefficient on the surfaces between these ribs and only a few studies report the heat transfer coefficient on the rib surfaces themselves. The present study investigated the heat transfer coefficient on the surfaces of round-corner, low-aspect-ratio (ARrib = 0.667) ribs. Twelve rib geometries, comprising three rib height-to-channel hydraulic diameters (blockage ratios) of 0.133, 0.167, and 0.25 as well as three rib spacings (pitch-to-height ratios) of 5, 8.5, and 10 were investigated for two distinct thermal boundary conditions of heated and unheated channel walls. A square channel, roughened with low-aspect-ratio ribs on two opposite walls in a staggered manner and perpendicular to the flow direction, was tested. An instrumented copper rib was positioned either in the middle of the rib arrangements or in the furthest upstream location. Both rib heat transfer coefficient and channel friction factor for these low-aspect-ratio ribs were also compared with those of square ribs, reported previously by the authors. Heat transfer coefficients of the furthest upstream rib and that of a typical rib located in the middle of the rib-roughened region of the passage wall were also compared.

Issue Section:
Research Papers
Topics:
Heat transfer coefficients, Cooling, Blades, Boundary-value problems, Cavities, Convection, Copper, Corners (Structural elements), Flow (Dynamics), Friction, Turbine blades
1.
Abuaf, N., Gibbs, R., and Baum, R., 1986, “Pressure Drop and Heat Transfer Coefficient Distributions in Serpentine Passages With and Without Turbulence Promoters,” Proc. Eighth International Heat Transfer Conference, Tien, C. L., Carey, V. P., and Ferrel, J. K., eds., pp. 2837–2845.
2.
Berger
F. P.
, and
Hau
K.-F.
,
1979
, “
Local Mass/Heat Transfer Distribution on Surfaces Roughened With Small Square Ribs
,”
Int. J. Heat Mass Transfer
, Vol.
22
, pp.
1645
–
1656
.
3.
Burggraf, F., 1970, “Experimental Heat Transfer and Pressure Drop With Two Dimensional Turbulence Promoters Applied to Two Opposite Walls of a Square Tube,” Augmentation of Convective Heat and Mass Transfer, A. E. Bergles and R. L. Webb, eds., ASME, pp. 70–79.
4.
Chandra
P. R.
,
Han
J. C.
, and
Lau
S. C.
,
1988
, “
Effect of Rib Angle on Local Heat/Mass Transfer Distribution in a Two-Pass Rib-Roughened Channel
,”
ASME JOURNAL OF TURBOMACHINERY
, Vol.
110
, pp.
233
–
241
.
5.
Chandra
P. R.
, and
Han
J. C.
,
1989
, “
Pressure Drop and Mass Transfer in Two-Pass Ribbed Channels
,”
AIAA Journal of Thermophysics
, Vol.
3
, No.
3
, pp.
315
–
319
.
6.
Colburn
,
1933
, “
A Method of Correlating Forced Convection Heat Transfer Data and a Comparison With Fluid Friction
,”
Trans. AIChE
, Vol.
29
, pp.
174
–
210
.
7.
Dawes
W. N.
,
1994
, “
The Solution-Adaptive Numerical Simulation of the 3D Viscous Flow in the Serpentine Coolant Passage of a Radial Inflow Turbine Blade
,”
ASME JOURNAL OF TURBOMACHINERY
, Vol.
116
, pp.
141
–
148
.
8.
Dittus, F. W., and Boelter, L. M. K., 1930, University of California, Berkeley, CA, Publications in Engineering, Vol. 2, pp. 443.
9.
El-Husayni
H. A.
,
Taslim
M. E.
, and
Kercher
D. M.
,
1991
, “
An Experimental Investigation of Heat Transfer Coefficients in a Spanwise Rotating Channel With Two Opposite Rib-Roughened Walls
,”
ASME JOURNAL OF TURBOMACHINERY
, Vol.
113
, pp.
75
–
82
.
10.
Gee
D. L.
, and
Webb
R. L.
,
1980
, “
Forced Convection Heat Transfer in Helically Rib-Roughened Tubes
,”
Int. J. Heat Mass Transfer
, Vol.
23
, pp.
1127
–
1136
.
11.
Han
J. C.
,
Glicksman
L. R.
, and
Rohsenow
W. M.
,
1978
, “
An Investigation of Heat Transfer and Friction for Rib Roughened Surfaces
,”
Int. J. Heat Mass Transfer
, Vol.
21
, pp.
1143
–
1156
.
12.
Han
J. C.
,
1984
, “
Heat Transfer and Friction in Channels With Two Opposite Rib-Roughened Walls
,”
ASME Journal of Heat Transfer
, Vol.
106
, pp.
774
–
781
.
13.
Han
J. C.
,
Park
J. S.
, and
Lei
C. K.
,
1985
, “
Heat Transfer Enhancement in Channels With Turbulence Promoters
,”
ASME Journal of Engineering for Gas Turbines and Power
, Vol.
107
, pp.
628
–
635
.
14.
Han
J. C.
,
Zhang
Y. M.
, and
Lee
C. P.
,
1992
, “
Influence of Surface Heat Flux Ratio on Heat Transfer Augmentation in Square Channels With Parallel, Crossed, and V-Shaped Angled Ribs
,”
ASME JOURNAL OF TURBOMACHINERY
, Vol.
114
, pp.
872
–
880
.
15.
Kline
S. J.
, and
McClintock
F. A.
,
1953
, “
Describing Uncertainty in Single-Sample Experiments
,”
Mechanical Engineering
, Vol.
75
, Jan., pp.
3
–
8
.
16.
Korotky, G. J., 1994, “An Experimental Investigation of the Rib Surface-Averaged Heat Transfer Coefficient in a Square Passage Roughened With Rounded Ribs of Two Aspect Ratios,” MS Thesis, Mechanical Engineering Dept., Northeastern University, Boston, MA.
17.
Korotky
G. J.
, and
Taslim
M. E.
,
1998
, “
An Experimental Investigation of the Rib Surface-Averaged Heat Transfer Coefficient in a Square Passage Roughened With Rounded Ribs of Two Aspect Ratios
,”
ASME JOURNAL OF TURBOMACHINERY
, Vol.
120
, pp.
376
–
385
.
18.
Liou
T. M.
,
Hwang
J. J.
, and
Chen
S. H.
,
1991
, “
Turbulent Heat Transfer and Fluid Flow in a Channel With Repeated Rib Pairs
,”
Proc. ASME/JSME Thermal Eng.
, Vol.
3
, pp.
205
–
212
.
19.
Liou
T. M.
, and
Hwang
J. J.
,
1993
, “
Effects of Ridge Shapes on Turbulent Heat Transfer and Friction in a Rectangular Channel
,”
Int. J. Heat Mass Transfer
, Vol.
36
, pp.
931
–
940
.
20.
Lockett
J. F.
, and
Collins
M. W.
,
1990
, “
Holographic Interferometry Applied to Rib-Roughness Heat Transfer in Turbulent Flow
,”
Int. J. Heat Mass Transfer
, Vol.
33
, pp.
2439
–
2449
.
21.
Metzger, D. E., Fan, C. S., and Pennington, J. W., 1983, “Heat Transfer and Flow Friction Characteristics of Very Rough Transverse Ribbed Surfaces With and Without Pin Fins,” Proc. ASME-JSME Thermal Engineering Joint Conference, Vol. 1, pp. 429–436.
22.
Metzger, D. E., Chyu, M. K., and Bunker, R. S., 1988, “The Contribution of On-Rib Heat Transfer Coefficients to Total Heat Transfer From Rib-Roughened Surfaces,” Transport Phenomena in Rotating Machinery, J. H. Kim, ed., Hemisphere Publishing Co.
23.
Metzger, D. E., Fan, C. S., and Yu, Y., 1990, “Effects of Rib Angle and Orientation on Local Heat Transfer in Square Channels With Angled Roughness Ribs,” Compact Heat Exchangers: A Festschrift for A. L. London, Hemisphere Publishing Co., pp. 151–167.
24.
Moody
L. F.
,
1944
, “
Friction Factors for Pipe Flow
,”
Trans. ASME
, Vol.
66
, p.
671
671
.
25.
Sato
H.
,
Hishida
K.
, and
Maeda
M.
,
1992
, “
Characteristics of Turbulent Flow and Heat Transfer in a Rectangular Channel With Repeated Rib Roughness
,”
Exp. Heat Transfer
, Vol.
5
, pp.
1
–
16
.
26.
Solntsev
V. P.
,
Luzhanskii
B. E.
, and
Kryukov
V. N.
,
1973
, “
An Investigation of Heat Transfer in the Turbulent Separation Zones in the Vicinity of Sudden Steps
,”
Heat Transfer—Soviet Research
, Vol.
5
, No.
2
, pp.
122
–
128
.
27.
Taslim, M. E., and Spring, S. D., 1988a, “An Experimental Investigation of Heat Transfer Coefficients and Friction Factors in Passages of Different Aspect Ratio Roughened With 45° Turbulators,” Proc. ASME National Heat Conference, Houston, TX.
28.
Taslim, M. E., and Spring, S. D., 1988b, “Experimental Heat Transfer and Friction Factors in Turbulated Cooling Passages of Different Aspect Ratios, Where Turbulators Are Staggered,” Paper No. AIAA-88-3014.
29.
Taslim
M. E.
, and
Spring
S. D.
,
1994
, “
Effects of Turbulator Profile and Spacing on Heat Transfer and Friction in a Channel
,”
AIAA J. Thermophysics and Heat Transfer
, Vol.
8
, No.
3
, pp.
555
–
562
.
30.
Taslim
M. E.
,
Rahman
A.
, and
Spring
S. D.
,
1991
a, “
An Experimental Investigation of Heat Transfer Coefficients in a Spanwise Rotating Channel With Two Opposite Rib-Roughened Walls
,”
ASME JOURNAL OF TURBOMACHINERY
, Vol.
113
, pp.
75
–
82
.
31.
Taslim
M. E.
,
Bondi
L. A.
, and
Kercher
D. M.
,
1991
b, “
An Experimental Investigation of Heat Transfer in an Orthogonally Rotating Channel Roughened With 45° Criss-Cross Ribs on Two Opposite Walls
,”
ASME JOURNAL OF TURBOMACHINERY
, Vol.
113
, pp.
346
–
353
.
32.
Taslim
M. E.
,
Li
T.
, and
Kercher
D. M.
,
1996
, “
Experimental Heat Transfer and Friction in Channels Roughened With Angled, V-Shaped, and Discrete Ribs on Two Opposite Walls
,”
ASME JOURNAL OF TURBOMACHINERY
, Vol.
118
, pp.
1
–
9
.
33.
Taslim
M. E.
, and
Wadsworth
C. M.
,
1997
, “
An Experimental Investigation of the Rib Surface-Averaged Heat Transfer Coefficient in a Rib-Roughened Square Passage
,”
ASME JOURNAL OF TURBOMACHINERY
, Vol.
119
, pp.
381
–
389
.
34.
Webb
R. L.
,
Eckert
E. R. G.
, and
Goldstein
R. J.
,
1971
, “
Heat Transfer and Friction in Tubes With Repeated-Rib-Roughness
,”
Int. J. Heat Mass Transfer
, Vol.
14
, pp.
601
–
617
.
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