Abstract

The flow field in a channel with staggered pin-fin array was measured using time-resolved Particle Imaging Velocimetry (PIV). The distributions of flow field statistics were compared with those of Nusselt number on the endwall measured by thermochromic liquid crystal (TLC) of the same geometry. Lower-order large-scale fluctuation and higher order small-scale disturbances were examined separately using Proper Orthogonal Decomposition (POD) to study the flow field characteristics and their individual effect on the heat transfer enhancement. Pin fins with circular and square cross-section geometries were studied at Reynolds numbers of 10,000 and 20,000. Results indicate that for circular pin fins, the distribution of lateral/transverse velocity fluctuations or turbulent kinetic energy from large-scale vortex shedding resembles that of local Nu, and the heat transfer augmentation downstream of the recirculation zone is dominant, while the heat transfer enhancement is limited in the shear layer on both sides of recirculation where disturbances are small scale. However, for square pin fins, heat transfer augmentation in the shear layer is as strong as that downstream of recirculation, while large-scale fluctuations downstream is much weaker than small scale disturbances in the shear layer. Compared to small-scale disturbances, large-scale fluctuations are found to contribute more efficiently to endwall heat transfer enhancement both for circular and for square pin fins. Large-scale fluctuation, as well as heat transfer enhancement, weakens with the increase in Reynolds number, while smaller-scale disturbance grows stronger at the same time.

References

1.
Chyu
,
M. K.
,
Hsing
,
Y. C.
, and
Natarajan
,
V.
,
1998
, “
Convective Heat Transfer of Cubic Fin Arrays in a Narrow Channel
,”
ASME J. Turbomach.
,
120
(
2
), pp.
362
367
.
2.
Metzger
,
D. E.
,
Fan
,
S. C.
, and
Haley
,
S. W.
,
1984
, “
Effects of Pin Shape and Array Orientation on Heat Transfer and Pressure Loss in Pin Fin Arrays
,”
ASME J. Eng. Gas Turbines Power
,
106
(
1
), pp.
252
257
.
3.
Chen
,
Z.
,
Li
,
Q.
,
Meier
,
D.
, and
Warnecke
,
H. J.
,
1997
, “
Convective Heat Transfer and Pressure Loss in Rectangular Ducts With Drop Shaped Pin Fins
,”
Heat Mass Transfer
,
33
(
3
), pp.
219
224
.
4.
Uzol
,
O.
, and
Camci
,
C.
,
2001
, “
Elliptical Pin Fins as an Alternative to Circular Pin Fins for Gas Turbine Blade Cooling Applications
,” ASME Paper No. GT2001-0180.
5.
Xu
,
J.
,
Yao
,
J. X.
,
Su
,
P. F.
,
Lei
,
J.
,
Wu
,
J. M.
, and
Gao
,
T. Y.
,
2017
, “
Heat Transfer and Pressure Loss Characteristics of Pin-Fins With Different Shapes in a Wide Channel
,” ASME Paper No. GT2017-63761.
6.
Park
,
J. S.
,
Kim
,
K. M.
,
Lee
,
D. H.
,
Cho
,
H. H.
, and
Chyu
,
M. K.
,
2008
, “
Heat Transfer Coefficient on Rotating Channel With Various Heights of Pin-Fin
,” ASME Paper No. GT2008-50783.
7.
Chyu
,
M. K.
,
Siw
,
S. C.
, and
Moon
,
H. K.
,
2009
, “
Effects of Height to Diameter Ratio of Pin Element on Heat Transfer From Staggered Pin-Fin Arrays
,” ASME Paper No. GT2009-59814.
8.
Lau
,
S. C.
,
Kim
,
Y. S.
, and
Han
,
J. C.
,
1987
, “
Local End Wall Heat/Mass-Transfer Distributions in Pin Fin Channels
,”
J. Thermophys.
,
1
(
4
), pp.
365
372
.
9.
Ostanek
,
J. K.
, and
Thole
,
K. A.
,
2013
, “
Effects of Non-uniform Streamwise Spacing in Low Aspect Ratio Pin Fin Arrays
,” ASME Paper No. GT2013-95889.
10.
Sparrow
,
E. M.
,
Ramsey
,
J. W.
, and
Altemani
,
C. A. C.
,
1980
, “
Experiments on In-line Pin Fin Arrays and Performance Comparisons With Staggered Arrays
,”
J. Heat Transfer
,
102
(
1
), pp.
44
55
.
11.
Goldstein
,
R.
, and
Karni
,
J.
,
1984
, “
The Effect of a Wall Boundary Layer on Local Mass Transfer From a Cylinder in Across Flow
,”
J. Heat Transfer
,
106
(
2
), pp.
260
267
.
12.
Chyu
,
M.
,
Hsing
,
Y.
,
Shih
,
T.-P.
, and
Natarajan
,
V.
,
1999
, “
Heat Transfer Contributions of Pins and End Wall in Pin-Fin Arrays: Effects of Thermal Boundary Condition Modeling
,”
ASME J. Turbomach.
,
121
(
2
), pp.
257
263
.
13.
Dargahi
,
B.
,
1989
, “
The Turbulent Flow Field Around a Circular Cylinder
,”
Exp. Fluids
,
8
(
1–2
), pp.
1
12
.
14.
Won
,
S.
,
Mahmood
,
G.
, and
Ligrani
,
P.
,
2004
, “
Spatially Resolved Heat Transfer and Flow Structure in a Rectangular Channel With Pin Fins
,”
Int. J. Heat Mass Transfer
,
47
(
8
), pp.
1731
1743
.
15.
Uzol
,
O.
, and
Camci
,
C.
,
2005
, “
Heat Transfer, Pressure Loss and Flow Field Measurements Downstream of Staggered Two-Row Circular and Elliptical Pin Fin Arrays
,”
J. Heat Transfer
,
127
(
5
), pp.
458
471
.
16.
Ames
,
F.
, and
Dvorak
,
L.
,
2006
, “
Turbulent Transport in Pin Fin Arrays: Experimental Data and Predictions
,”
ASME J. Turbomach.
,
128
(
1
), pp.
71
81
.
17.
Otto
,
M.
,
Hodges
,
J.
,
Gupta
,
G.
, and
Kapat
,
J. S.
,
2019
, “
Vortical Structures in Pin Fin Arrays for Turbine Cooling Applications
,” ASME Paper No. GT2019-90552.
18.
Ostanek
,
J. K.
, and
Thole
,
K. A.
,
2012
, “
Effect of Streamwise Spacing on Periodic and Random Unsteadiness in a Bundle of Short Cylinders Confined in a Channel
,”
Exp. Fluids
,
53
(
6
), pp.
1779
1796
.
19.
Han
,
J. C.
,
2006
, “
Turbine Blade Cooling Studies at Texas A&M University: 1980–2004
,”
J. Thermophys. Heat Transfer
,
20
(
2
), pp.
161
187
.
20.
Son
,
S. Y.
,
Kihm
,
K. D.
, and
Han
,
J. C.
,
2002
, “
PIV Flow Measurements for Heat Transfer Characterization in Two-Pass Square Channels With Smooth and 90 Ribbed Walls
,”
Int. J. Heat Mass Transfer
,
45
(
24
), pp.
4809
4822
.
21.
Delibra
,
G.
,
Hanjalić
,
K.
,
Borello
,
D.
, and
Rispoli
,
F.
,
2010
, “
Vortex Structures and Heat Transfer in a Wall-Bounded Pin Matrix: LES With a RANS Wall-Treatment
,”
Int. J. Heat Fluid Flow
,
31
(
5
), pp.
740
753
.
22.
Ostanek
,
J. K.
, and
Thole
,
K. A.
,
2012
, “
Flowfield Measurements in a Single Row of Low Aspect Ratio Pin Fins
,”
ASME J. Turbomach.
,
134
(
5
), p.
051034
.
23.
Shi
,
L.
,
2010
, “
Experimental Study and POD Analysis of Unsteady Characteristic of the Wake Behind a Near-Wall Square Cylinder
,”
Ph. D dissertation
,
Shanghai Jiaotong Univeisity
,
Shanghai, China
.
24.
Holmes
,
P.
,
Lumley
,
J. L.
,
Berkooz
,
G.
, and
Rowley
,
C. W.
,
2012
,
Turbulence, Coherent Structures, Dynamical Systems and Symmetry
,
Cambridge University Press
,
New York
.
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