Short pin-fin arrays are often used for cooling turbine airfoils, particularly near the trailing edge. An accurate heat transfer estimation from a pin-fin array should account for the total heat transfer over the entire wetted surface, which includes the pin surfaces and uncovered endwalls. One design question frequently raised is the actual magnitudes of heat transfer coefficients on both pins and endwalls. Results from earlier studies have led to different and often contradicting conclusions. This variation, in part, is caused by imperfect or unrealistic thermal boundary conditions prescribed in the individual test models. Either pins or endwalls, but generally not both, were heated in those previous studies. Using a mass transfer analogy based on the naphthalene sublimation technique, the present experiment is capable of revealing the individual heat transfer contributions from pins and endwalls with the entire wetted surface thermally active. The particular pin-fin geometry investigated, S/D = X/D = 2.5 and H/D = 1.0, is considered to be one of the optimal array arrangement for turbine airfoil cooling. Both inline and staggered arrays with the identical geometric parameters are studied for 5000 ≤ Re ≤ 25,000. The present results reveal that the general trends of the row-resolved heat transfer coefficients on either pins or endwalls are somewhat insensitive to the nature of thermal boundary conditions prescribed on the test surface. However, the actual magnitudes of heat transfer coefficients can be substantially different, due to variations in the flow bulk temperature. The present study also concludes that the pins have consistently 10 to 20 percent higher heat transfer coefficient than the endwalls. However, such a difference in heat transfer coefficient imposes very insignificant influence on the overall array-averaged heat transfer, since the wetted area of the uncovered endwalls is nearly four times greater than that of the pins.

1.
Al Dabagh, A. M., and Andrews, G. E., 1992, “Pin-Fin Heat Transfer: Contribution of the Wall and the Pin to the Overall Heat Transfer,” ASME Paper No. 92-GT-242.
2.
Ambrose, D., Lawenson, I. J., and Sprake, C. H. S., 1975, “The Vapor Pressure of Naphthalene,” J. Chem. Thermo., pp. 1173–1176.
3.
Armstrong
J.
, and
Winstanley
D.
,
1988
, “
A Review of Staggered Array Pin Fin Heat Transfer for Turbine Cooling Applications
,”
ASME JOURNAL OF TURBOMACHINERY
, Vol.
110
, pp.
94
103
.
4.
Brigham
B. A.
, and
VanFossen
G. J.
,
1984
, “
Length-to-Diameter Ratio and Row Number Effects in Short Pin Fin Heat Transfer
,”
ASME Journal of Engineering for Gas Turbines and Power
, Vol.
106
, pp.
241
246
.
5.
Chyu
M. K.
,
1990
, “
Heat Transfer and Pressure Drop for Short Pin-Fin Arrays With Pin-Endwall
,”
ASME Journal of Heat Transfer
, Vol.
112
, pp.
926
932
.
6.
Chyu
M. K.
, and
Goldstein
R. J.
,
1991
, “
Influence of Cylindrical Elements on Local Mass Transfer From a Flat Surface
,”
Int. J. Heat Mass Transfer
, Vol.
34
, pp.
2175
2186
.
7.
Chyu
M. K.
,
Hsing
Y. C.
, and
Natarajan
V.
,
1998
, “
Convective Heat Transfer of Cubic Fin Array in a Narrow Channel
,”
ASME JOURNAL OF TURBOMACHINERY
, Vol.
120
, pp.
362
367
.
8.
Eckert, E. R. G., 1976, “Analogies to Heat Transfer Processes,” Measurements in Heat Transfer, Eckert, E. R. G., and Goldstein, R. J., eds., Hemisphere Publishing Corp., New York.
9.
Metzger
D. E.
,
Berry
R. A.
, and
Benson
J. P.
,
1982
a, “
Developing Heat Transfer in Rectangular Ducts With Staggered Arrays of Short Pin Fins
,”
ASME Journal of Heat Transfer
, Vol.
104
, pp.
700
706
.
10.
Metzger, D. E., and Haley, S. W., 1982b, “Heat Transfer Experiments and Flow Visualization of Arrays of Short Pin Fins,” ASME Paper No. 82-GT-138.
11.
Metzger, D. E., Fan, Z. X., and Sheppard, W. B., 1982c, “Pressure Loss and Heat Transfer Through Multiple Rows of Short Pin Fins,” Heat Transfer 1982, Vol. 3, Hemisphere Publishing Corp., pp. 137–142.
12.
Metzger
D. E.
,
Fan
C. S.
, and
Haley
S. W.
,
1984
, “
Effects if Pin Shape and Array Orientation on Heat Transfer and Pressure Loss in Pin Fin Arrays
,”
ASME Journal of Engineering for Gas Turbines and Power
, Vol.
106
, pp.
252
257
.
13.
Metzger, D. E. and Sheppard, W. B., 1986, “Row Resolved Heat Transfer Variations in Pin Fin Arrays Including Effects of Non-uniform Arrays and Flow Convergence,” ASME Paper No. 86-GT-132.
14.
Natarajan, V., and Chyu, M. K., 1994, “Convective Heat Transfer From Finite Cylinders Mounted on a Plane Wall,” Paper No. 4-EC-15, Vol. 3, pp. 71–77, 10th International Heat Transfer Conference, Brighton, UK, Aug. 14–18.
15.
Simoneau
R. J.
, and
VanFossen
G. J.
,
1984
, “
Effect of Location in an Array on Heat Transfer to a Short Cylinder in Crossflow
,”
ASME Journal of Heat Transfer
, Vol.
106
, pp.
42
48
.
16.
Sparrow
E. M.
, and
Ramsey
J. M.
,
1978
, “
Heat Transfer and Pressure Drop for a Staggered Wall-Attached Array of Cylinders With Tip Clearance
,”
Int. J. Heat Mass Transfer
, Vol.
21
, pp.
44
50
.
17.
VanFossen
G. J.
,
1982
, “
Heat Transfer Coefficient for Staggered Arrays of Short Pin Fins
,”
ASME Journal of Engineering for Power
, Vol.
104
, pp.
268
274
.
18.
Zukauskas
A. A.
,
1972
, “
Heat Transfer From Tubes in Cross Flow
,”
Advances in Heat Transfer
, Vol.
8
, pp.
116
133
.
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