This paper presents a comparative numerical study of turbulent flow inside a two-pass internal cooling channel with different bend geometries. The goal is to find a geometry that reduces the bend related pressure loss and enhances overall heat transfer coefficient. A square channel with a round U-bend is taken as a baseline case and the heat transfer and pressure drop for nine different bend geometries are compared with the baseline. Modifications for the bend geometry are made along the channel divider wall and at the end wall of the 180 deg bend. The bend geometries studied include: (1) a turning vane geometry, (2) an asymmetrical bulb, (3) three different symmetrical bulbs, (4) two different bow shaped geometries at the end wall, (5) a bend with an array of dimples in the bend region, and (6) finally a combination of bow geometry and dimples. The solution procedure is based on a commercial finite volume solver using the Reynolds averaged Navier–Stokes (RANS) equation and a turbulence model. A two equation realizable k-ɛ model with enhanced wall treatment is used to model the turbulent flow. It was found that the bend geometry can have a significant effect on the overall performance of a two-pass channel. The modified bend geometries are compared with the baseline using Nusselt number ratios, friction factor ratios, and thermal performance factors (TPF) as the metrics. All the modified bend geometries show increase in the TPF with the symmetrical bulb configuration showing nearly a 40% reduction in friction factor ratio and a 30% increase in thermal performance. The highest TPF (41% increase over baseline) is observed for the symmetrical bulb combined with a bow along the outer walls and surface dimples.

References

References
1.
Metzger
,
D. E.
,
Plevich
,
C. W.
, and
Fan
,
C. S.
,
1984
, “
Pressure Loss Through Sharp 180° Turns in Smooth Rectangular Channels
,”
ASME J. Eng. Gas Turb. Power
,
106
, pp.
677
681
.10.1115/1.3239623
2.
Metzger
,
D. E.
, and
Plevich
,
C. W.
,
1990
, “
Effects of Turn Region Treatments on Pressure Loss Through Sharp 180° Bends
,”
Proceedings of Third International Symposium on Transport Phenomena and Dynamics of Rotating Machinery (ISROMAC-3)
,
Honolulu
,
HI
, pp.
301
312
.
3.
Schabacker
,
J.
,
Bolcs
,
A.
, and
Johnson
,
B. V.
,
1998
, “
PIV Investigation of the Flow Characteristics in an Internal Coolant Passage With Two Ducts Connected by a Sharp 180° Bend
,”
Proceedings of the ASME Turbo Expo 1998,
Stockholm, Sweden
, Paper No. GT1998-544.
4.
Liou
,
T. M.
,
Tzeng
,
Y. Y.
, and
Chen
,
C. C.
,
1999
, “
Fluid Flow in a 180 Deg Sharp Turning Duct With Different Divider Thicknesses
,”
ASME J. Turbomach.
,
121
, pp.
569
576
.10.1115/1.2841354
5.
Liou
,
T. M.
,
Chen
,
C. C.
,
Tzeng
,
Y. Y.
, and
Tsai
,
T. W.
,
2000
, “
Non-intrusive Measurements of Near-Wall Fluid Flow and Surface Heat Transfer in a Serpentine Passage
,”
Int. J. Heat Mass Transf.
,
43
, pp.
3233
3244
.10.1016/S0017-9310(99)00336-1
6.
Hirota
,
M.
Fujita
,
H.
Syuhada
,
A.
Araki
,
S.
Yoshida
,
T.
and
Tanaka
,
T.
,
1999
, “
Heat/Mass Transfer Characteristics in Two-Pass Smooth Channels With a Sharp 180-Deg Turn
,”
Int. J. Heat Mass Transf.
,
42
, pp.
3757
3770
.10.1016/S0017-9310(99)00057-5
7.
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 Transf.
,
45
, pp.
4809
4822
.10.1016/S0017-9310(02)00192-8
8.
Hirota
,
M.
,
Fujita
,
H.
,
Cai
,
L.
,
Nakayama
,
H.
,
Yanagida
,
M.
, and
Syafa’at
,
A.
,
2002
, “
Heat(Mass) Transfer in Rectangular Cross-Sectioned Two-Pass Channels With an Inclined Divider Wall
,”
Int. J. Heat Mass Transf.
,
45
, pp.
1093
1107
.10.1016/S0017-9310(01)00212-5
9.
Rao
,
D. V. R.
,
Babu
,
C. S.
, and
Prabhu
,
S. V.
,
2004
, “
Effect of Turn Region Treatments on the Pressure Loss Distribution in a Smooth Square Channel With a Sharp 180° Bend
,”
Int. J. Rotating Mach.
,
10
, pp.
459
468
.10.1155/S1023621X04000454
10.
Nakayama
,
H.
,
Hirota
,
M.
,
Fujita
,
H.
,
Yamada
,
T.
, and
Koide
,
Y.
,
2006
, “
Fluid Flow and Heat Transfer in Two-Pass Smooth Rectangular Channels With Different Turn Clearances
,”
ASME J. Turbomach.
,
128
, pp.
772
785
.10.1115/1.2101854
11.
Chang
,
S. W.
, and
Cai
,
Z. X.
,
2010
, “
Heat Transfer and Pressure Drop in Two-Pass Rib-Roughened Square Channels With Bleed From Sharp Bend
,”
Int. J. Heat Fluid Fl.
,
31
, pp.
19
31
.10.1016/j.ijheatfluidflow.2009.11.001
12.
Wang
,
T. S.
, and
Chyu
,
M. K.
,
1994
, “
Heat Convection in a 180 Deg Turning Duct With Different Turn Configurations
,”
J. Thermophys. Heat Tr
,
8
, pp.
595
601
.10.2514/3.583
13.
Iacovides
,
H.
, and
Raisee
,
M.
,
1999
, “
Recent Progress in the Computation of Flow and Heat Transfer in Internal Cooling Passages of Turbine Blades
,”
Int. J. Heat Fluid Fl.
,
20
, pp.
320
328
.10.1016/S0142-727X(99)00018-1
14.
Chen
,
H. C.
,
Jang
,
Y. J.
, and
Han
,
J. C.
,
2000
, “
Computation of Heat Transfer in Rotating Two-Pass Square Channels by a Second-Moment Closure Model
,”
Int. J. Heat Mass Transf.
,
43
, pp.
1603
1616
.10.1016/S0017-9310(99)00227-6
15.
Wagner
,
J. H.
,
Johnson
,
B. V.
, and
Kopper
,
F. C.
,
1991
, “
Heat Transfer in Rotating Serpentine Passage With Smooth Walls
,”
ASME J. Turbomach.
,
113
, pp.
321
330
.10.1115/1.2927879
16.
Murata
,
A.
, and
Mochizuki
,
S.
,
2000
, “
Large Eddy Simulation With a Dynamic Subgrid-Scale Model of Turbulent Heat Transfer in an Orthogonally Rotating Rectangular Duct With Transverse Rib Turbulators
,”
Int. J. Heat Mass Transf.
,
43
, pp.
1243
1249
.10.1016/S0017-9310(99)00205-7
17.
Lin
,
Y. L.
,
Shih
,
T. I. P.
,
Stephens
,
M. A.
, and
Chyu
,
M. K.
,
2001
, “
A Numerical Study of Flow and Heat Transfer in a Smooth and Ribbed U-Duct With and Without Rotation
,”
ASME J. Heat Transfer
,
123
, pp.
219
232
.10.1115/1.1345888
18.
Su
,
G.
,
Chen
,
H. C.
,
Han.
,
J. C.
, and
Heidmann
,
J. D.
,
2004
, “
Computation of Flow and Heat Transfer in Two-Pass Rotating Rectangular Channels (AR = 1:1, AR = 1:2, AR = 1:4) with 45-Deg Angled Ribs by a Reynolds Stress Turbulence Model
,”
Proceedings of the ASME Turbo Expo 2004
,
Vienna, Austria
, Paper No. GT2004-53662,
19.
Viswanathan
,
A. K.
, and
Tafti
,
D. K.
,
2006
, “
Detached Eddy Simulation of Turbulent Flow and Heat Transfer in a Two-Pass Internal Cooling Duct
,”
Int. J. Heat Fluid Fl.
,
27
, pp.
1
20
.10.1016/j.ijheatfluidflow.2005.07.002
20.
Sewall
,
E. A.
, and
Tafti
,
D. K.
,
2005
, “
Large Eddy Simulation of Flow and Heat Transfer in the 180° Bend Region of a Stationary Ribbed Gas Turbine Internal Cooling Duct
,”
Proceedings of the ASME Turbo Expo 2005
,
Reno-Tahoe, NV
, Paper No. GT2005-68518.
21.
Walker
,
D.
, and
Zausner
,
J.
,
2007
, “
RANS Evaluation of Internal Cooling Passage Geometries: Ribbed Passage and a 180 Degree Bend
,”
Proceedings of the ASME Turbo Expo 2007
,
Montreal, Canada
, Paper No. GT2007-27830.
22.
Namgoong
,
H.
,
Son
,
C.
, and
Ireland
,
P.
,
2008
, “
U-Bend Shaped Turbine Blade Cooling Passage Optimization
,”
12th American Institute of Aeronautics and Astronautics/International Society for Structural and Multidisciplinary Optimization Multidisciplinary Analysis and Optimization Conference
,
Victoria, Canada
.
23.
Luo
,
J.
, and
Razinsky
,
E. H.
,
2009
, “
Analysis of Turbulent Flow in 180 Deg Turning Ducts With and Without Guide Vanes
,”
ASME J. Turbomach.
,
131
, pp.
021011-1
021011-10
.10.1115/1.2987239
24.
Zehnder
,
F.
,
Schuler
,
M.
,
Weigand
,
B.
,
Wolfersdorf
,
J. V.
, and
Neumann
,
S. O.
,
2009
, “
The Effect of Turning Vanes on Pressure Loss and Heat Transfer of a Ribbed Rectangular Two-Pass Internal Cooling Channel
,”
Proceedings of the ASME Turbo Expo 2009,
Orlando, FL
, Paper No. GT2009-59482.
25.
Chen
,
W.
,
Ren
,
J.
, and
Jiang
,
H.
,
2010
, “
Effect of Turning Vane Configurations on Heat Transfer and Pressure Drop in a Ribbed Internal Cooling System
,”
Proceedings of the ASME Turbo Expo 2010,
Glasgow, UK
, Paper No. GT2010-22273.
26.
Ligrani
,
P. M.
, and
Oliveira.
,
M. M.
,
2003
, “
Comparison of Heat Transfer Augmentation Techniques
,”
AIAA J.
,
41
, pp.
337
362
.10.2514/2.1964
27.
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
,
13
, pp.
3442
3451
.10.1063/1.1404139
28.
Burgess
,
N. K.
,
Oliveira
,
M. M.
, and
Ligrani
,
P. M.
,
2003
, “
Nusselt Number Behavior on Deep Dimpled Surface Within a Channel
,”
ASME J. Heat Transfer
,
125
, pp.
11
18
.10.1115/1.1527904
29.
Samad
,
A.
,
Lee
,
K. D.
, and
Kim
,
K. Y.
,
2008
, “
Multi-Objective Optimization of a Dimpled Channel for Heat Transfer Augmentation
,”
Heat Mass Transf.
,
45
, pp.
207
217
.10.1007/s00231-008-0420-6
30.
Schuler
,
M.
,
Zehnder
,
F.
,
Weigand
,
B.
,
Wolfersdorf
,
J. V.
, and
Neumann
,
S. O.
,
2011
, “
The Effect of Side Wall Mass Extraction on Pressure Loss and Heat Transfer of a Ribbed Rectangular Two-Pass Internal Cooling Channel
,”
ASME J. Turbomach.
,
133
, pp.
021002-1
021002-11
.
31.
Wilcox
,
D. C.
,
2006
, “
Turbulence Modeling for CFD
,”
3rd Ed.
,
DCW Industries, Incorporated
,
La Canada, CA
.
32.
Fluent Inc.
,
2006
,
Fluent 6.3 User’s Guide
, pp.
443
461
.
33.
Dittus
,
F. W.
, and
Boelter
,
L. M. K.
,
1930
,
Publications on Engineering
,
2
,
University of California
,
Berkeley, CA
, p.
443
.
34.
Kays
,
W. M.
, and
Crawford
,
M. E.
,
1993
,
Convective Heat and Mass Transfer
,
3rd ed.
,
McGraw–Hill
,
New York
.
35.
Saha
,
K.
, and
Acharya
,
S.
,
2011
, “
Effect of Entrance Geometry on Heat Transfer in a Narrow (AR = 1:4) Rectangular Two Pass Channel With Smooth and Ribbed Walls
,”
Proceedings of the ASME Turbo Expo 2011,
Vancouver, Canada
, Paper No. GT2011-46076.
36.
Dean
,
W. R.
,
1928
, “
Fluid Motion in a Curved Channel
,”
Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character
,
121
, pp.
402
420
.
You do not currently have access to this content.