The present study investigates the heat transfer performance of W-shaped ribs in a rectangular channel with typical geometries and flow conditions for a combustor liner cooling passage. In order to assess the Reynolds number dependence on heat transfer enhancement by the ribs for the combustor cooling passage, experiments were conducted with channel Reynolds number ranging from 40,000 to 550,000. The ribs were located on one side of the channel and the rib height-to-hydraulic diameter ratio $(e/Dh)$ was 0.006–0.014, which simulate the combustor liner cooling configurations. Rib pitch-to-height ratio $(P/e)$ was 10. Rib-roughened copper plates with constant temperature were used to measure the averaged heat transfer coefficients. Measured results show that the heat transfer enhancements of about 3 were obtained over that of a flat plate at high Reynolds numbers for all cases. The slope of heat transfer coefficient becomes constant with increasing Reynolds number because of the laminar-turbulent transition around the ribs, which is considered to occur at Reynolds number based on rib height of about 1000. Pressure loss measurements showed that the friction coefficients are constantly 3–4.5 times higher than those of a flat plate for a fully turbulent flow such as a combustor cooling passage. Pressure loss by ribs seems not to have a significant impact to the overall combustor performance. Numerical calculations were conducted additionally for all test cases. Predicted amount of heat released from the ribs contributes about 40% of the overall heat release even for low ribs. Heat transfer on the rib surface is essential in the evaluation of the rib-roughened cooling passage.

1.
Han
,
J. C.
,
Park
,
J. S.
, and
Lei
,
C. K.
, 1985, “
Heat Transfer Enhancement in Channels With Turbulence Promoters
,”
ASME J. Eng. Gas Turbines Power
0742-4795,
107
, pp.
628
635
.
2.
Taslim
,
M. E.
, and
Spring
,
S. D.
, 1994, “
Effects of Turbulator Profile and Spacing on Heat Transfer and Friction in a Channel
,”
J. Thermophys. Heat Transfer
0887-8722,
8
(
3
), pp.
555
562
.
3.
Taslim
,
M. E.
, and
,
C. M.
, 1994, “
An Experimental Investigation of the Rib Surface-Averaged Heat Transfer Coefficient in a Rib-Roughened Square Passage
,”
ASME
Paper No. 94-GT-162.
4.
Taslim
,
M. E.
, and
Korotky
,
G. J.
, 1997, “
Low-Aspect-Ratio Rib Heat Transfer Coefficient Measurements in a Square Channel
,”
ASME
Paper No. 97-GT-388.
5.
Taslim
,
M. E.
, and
Lengkong
,
A.
, 1998, “
45° Round-Corner Rib Heat Transfer Coefficient Measurements in a Square Channel
,”
ASME
Paper No. 98-GT-176.
6.
Liu
,
Y. H.
,
Wright
,
L. M.
,
Fu
,
W. L.
, and
Han
,
J. C.
, 2006, “
Rib Spacing Effect on Heat Transfer and Pressure Loss in a Rotating Two-Pass Rectangular Channel (AR=1:2) With 45-Degree Angled Ribs
,”
ASME
Paper No. GT2006-90368.
7.
Han
,
J. C.
,
Zhang
,
Y. M.
, and
Lee
,
C. P.
, 1991, “
Augmented Heat Transfer in Square Channels With Parallel, Crossed, and V-Shaped Angled Ribs
,”
ASME J. Heat Transfer
0022-1481,
113
, pp.
590
596
.
8.
Lee
,
E.
,
Wright
,
L. M.
, and
Han
,
J. C.
, 2003, “
Heat Transfer in Rotating Rectangular Channels (AR=4:1) With V-Shaped and Angled Rib Turbulators With and Without Gaps
,”
ASME
Paper No. GT2003-38900.
9.
Su
,
G.
,
Teng
,
S.
,
Chen
,
H. C.
, and
Han
,
J. C.
, 2003, “
Computation of Flow and Heat Transfer in Rotating Rectangular Channels (AR=4) With V-Shaped Ribs by a Reynolds Stress Turbulence Model
,”
ASME
Paper No. GT2003-38348.
10.
Wright
,
L. M.
,
Fu
,
W. L.
, and
Han
,
J. C.
, 2004, “
Thermal Performance of Angled, V-Shaped, and W-Shaped Rib Turbulators in Rotating Rectangular Cooling Channels (AR=4:1)
,”
ASME
Paper No. GT2004-54073.
11.
Kim
,
Y. W.
,
Arellano
,
L.
,
Vardakas
,
M.
,
Moon
,
H. K.
, and
Smith
,
K. O.
, 2003, “
Comparison of Trip-Strip/Impingement/Dimple Cooling Concepts at High Reynolds Numbers
,”
ASME
Paper No. GT2003-38935.
12.
Maurer
,
M.
,
Wolfersdorf
,
J.
, and
Gritsch
,
M.
, 2006, “
Experimental and Numerical Study of Heat Transfer and Pressure Loss in a Rectangular Channel With V-Shaped Ribs
,”
ASME
Paper No. GT2006-90006.
13.
Maurer
,
M.
,
Wolfersdorf
,
J.
, and
Gritsch
,
M.
, 2007, “
An Experimental and Numerical Study of Heat Transfer and Pressure Losses of V- and W-Shaped Ribs at High Reynolds Numbers
,”
ASME
Paper No. GT2007-27167.
14.
Maurer
,
M.
,
Ruedel
,
U.
,
Gritsch
,
M.
, and
Wolfersdorf
,
J.
, 2008, “
Experimental Study of Advanced Convective Cooling Techniques for Combustor Liners
,”
ASME
Paper No. GT2008-51026.
15.
Kunstmann
,
S.
,
Wolfersdorf
,
J.
, and
Ruedel
,
U.
, 2009, “
Heat Transfer and Pressure Loss in Rectangular One-Side-Ribbed Channels With Different Aspect Ratios
,”
ASME
Paper No. GT2009-59333.
16.
JSME
, 1979, JSME Data Book: Hydraulic Losses in Pipes and Ducts, Maruzen, Tokyo.
17.
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
.
18.
Abe
,
K.
,
Kondoh
,
T.
, and
Nagano
,
Y.
, 1994, “
A New Turbulence Model for Predicting Fluid Flow and Heat Transfer in Separating and Reattaching Flows—1. Flow Field Calculations
,”
Int. J. Heat Mass Transfer
0017-9310,
37
(
1
), pp.
139
151
.