Abstract

Turbulators are a promising avenue to enhance heat transfer in a wide variety of applications. An experimental and numerical investigation of heat transfer and pressure drop of a broken V (chevron) turbulator is presented at Reynolds numbers ranging from approximately 300,000 to 900,000 in a rectangular channel with an aspect ratio (width/height) of 1.29. The rib height is 3% of the channel hydraulic diameter, while the rib spacing to rib height ratio is fixed at 10. Heat transfer measurements are performed on the flat surface between ribs using transient liquid crystal (LC) thermography. The experimental results reveal a significant increase of the heat transfer and friction factor of the ribbed surface compared with a smooth channel. Both parameters increase with Reynolds number, with a heat transfer enhancement ratio of up to 2.15 (relative to a smooth channel) and a friction factor ratio of up to 6.32 over the investigated Reynolds number range. Complementary computational fluid dynamics (CFD) Reynolds-averaged Navier–Stokes (RANS) simulations are performed with the κ-ω shear-stress transport (SST) turbulence model in ansys fluent® 17.1, and the numerical estimates are compared against the experimental data. The results reveal that the discrepancy between the experimentally measured area-averaged Nusselt number and the numerical estimates increases from approximately 3% to 13% with increasing Reynolds number from 339,000 to 917,000. The numerical estimates indicate turbulators enhance heat transfer by interrupting the boundary layer as well as increasing near surface turbulent kinetic energy (TKE) and mixing.

References

1.
Tamna
,
S.
,
Kaewkohkiat
,
Y.
,
Skullong
,
S.
, and
Promvonge
,
P.
,
2016
, “
Heat Transfer Enhancement in Tubular Heat Exchanger With Double V-Ribbed Twisted-Tapes
,”
Case Stud. Therm. Eng.
,
7
, pp.
14
24
.
2.
Hagari
,
T.
,
Ishida
,
K.
,
Oda
,
T.
,
Douura
,
Y.
, and
Kinoshita
,
Y.
,
2011
, “
Heat Transfer and Pressure Losses of W-Shaped Small Ribs at High Reynolds Numbers for Combustor Liner
,”
ASME J. Eng. Gas Turbines Power
,
133
(
9
), p.
091901
.
3.
Lörstad
,
D.
,
2012
, “
LES and RANS Assessment of Rib Cooled Channel Related to SGT-800 Combustor Liner
,”
ASME Paper No. GT2011-46415
.
4.
Maurer
,
M.
,
von Wolfersdorf
,
J.
, and
Gritsch
,
M.
,
2007
, “
An Experimental and Numerical Study of Heat Transfer and Pressure Loss in a Rectangular Channel With V-Shaped Ribs
,”
ASME J. Turbomach.
,
129
(
4
), pp.
800
808
.
5.
Maurer
,
M.
,
von 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
.
6.
Rallabandi
,
A. P.
,
Alkhamis
,
N.
, and
Han
,
J. C.
,
2011
, “
Heat Transfer and Pressure Drop Measurements for a Square Channel With 45 deg Round-Edged Ribs at High Reynolds Numbers
,”
ASME J. Turbomach.
,
133
(
3
), p.
031019
.
7.
Zhang
,
M.
,
Singh
,
P.
, and
Ekkad
,
S. V.
,
2019
, “
Rib Turbulator Heat Transfer Enhancements at Very High Reynolds Numbers
,”
ASME J. Therm. Sci. Eng. Appl.
,
11
(
6
), p.
061014
.
8.
Mhetras
,
S.
,
Han
,
J. C.
, and
Huth
,
M.
,
2014
, “
Heat Transfer and Pressure Loss Measurements in a Turbulated High Aspect Ratio Channel With Large Reynolds Number Flows
,”
ASME J. Therm. Sci. Eng. Appl.
,
6
(
4
), p.
041001
.
9.
Gupta
,
A.
,
SriHarsha
,
V.
,
Prabhu
,
S. V.
, and
Vedula
,
R. P.
,
2008
, “
Local Heat Transfer Distribution in a Square Channel With 90 deg Continuous, 90 deg Saw Tooth Profiled and 60 deg Broken Ribs
,”
Exp. Therm. Fluid Sci.
,
32
(
4
), pp.
997
1010
.
10.
Han
,
J. C.
, and
Zhang
,
Y. M.
,
1992
, “
High Performance Heat Transfer Ducts With Parallel Broken and V-Shaped Broken Ribs
,”
Int. J. Heat Mass Transfer
,
35
(
2
), pp.
513
523
.
11.
SriHarsha
,
V.
,
Prabhu
,
S. V.
, and
Vedula
,
R. P.
,
2009
, “
Influence of Rib Height on the Local Heat Transfer Distribution and Pressure Drop in a Square Channel With 90 deg Continuous and 60 deg V-Broken Ribs
,”
Appl. Therm. Eng.
,
29
(
11–12
), pp.
2444
2459
.
12.
Kiml
,
R.
,
Mochizuki
,
S.
, and
Murata
,
A.
,
2001
, “
Effects of Rib Arrangements on Heat Transfer and Flow Behavior in a Rectangular Rib-Roughened Passage: Application to Cooling of Gas Turbine Blade Trailing Edge
,”
J. Heat Transfer
,
123
(
4
), pp.
675
681
.
13.
Han
,
J. C.
,
Ou
,
S.
,
Park
,
J. S.
, and
Lei
,
C. K.
,
1989
, “
Augmented Heat Transfer in Rectangular Channels of Narrow Aspect Ratios With Rib Turbulators
,”
Int. J. Heat Mass Transfer
,
32
(
9
), pp.
1619
1630
.
14.
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
,
107
(
3
), pp.
628
635
.
15.
Han
,
J. C.
, and
Park
,
J. S.
,
1988
, “
Developing Heat Transfer in Rectangular Channels With Rib Turbulators
,”
Int. J. Heat Mass Transfer
,
31
(
1
), pp.
183
195
.
16.
Promvonge
,
P.
,
Changcharoen
,
W.
,
Kwankaomeng
,
S.
, and
Thianpong
,
C.
,
2011
, “
Numerical Heat Transfer Study of Turbulent Square-Duct Flow Through Inline V-Shaped Discrete Ribs
,”
Int. Commun. Heat Mass Trans.
,
38
(
10
), pp.
1392
1399
.
17.
Tang
,
X. Y.
, and
Zhu
,
D. S.
,
2013
, “
Flow Structure and Heat Transfer in a Narrow Rectangular Channel With Different Discrete Rib Arrays
,”
Chem. Eng. Process.
,
69
, pp.
1
14
.
18.
Versteeg
,
H. K.
, and
Malalasekera
,
W.
,
2007
,
An Introduction to Computational Fluid Dynamics: The Finite Volume Method
, 2nd ed.,
Pearson Education Ltd.
,
UK
, pp.
97
98
.
19.
Choi
,
E. Y.
,
Choi
,
Y. D.
,
Lee
,
W. S.
,
Chung
,
J. T.
, and
Kwak
,
J. S.
,
2013
, “
Heat Transfer Augmentation Using a Rib–Dimple Compound Cooling Technique
,”
Appl. Therm. Eng.
,
51
(
1–2
), pp.
435
441
.
20.
Chaube
,
A.
,
Sahoo
,
P. K.
, and
Solanki
,
S. C.
,
2006
, “
Analysis of Heat Transfer Augmentation and Flow Characteristics Due to Rib Roughness Over Absorber Plate of a Solar Air Heater
,”
Renew. Energy
,
31
(
3
), pp.
317
331
.
21.
Han
,
J. C.
,
Dutta
,
S.
, and
Ekkad
,
S. V.
,
2000
,
Gas Turbine Heat Transfer and Cooling Technology
,
Taylor & Francis
,
New York
.
22.
Ghorbani-Tari
,
Z.
,
Sunden
,
B.
, and
Tanda
,
G.
,
2011
, “
On Liquid Crystal Thermography for Determination of the Heat Transfer Coefficient in Rectangular Ducts
,”
Proceedings of 15th International Conference on Computational Methods and Experimental Measurements
,
New Forest, UK
, pp.
255
266
.
23.
Ireland
,
P. T.
, and
Jones
,
T. V.
,
2000
, “
Liquid Crystal Measurements of Heat Transfer and Surface Shear Stress
,”
Meas. Sci. Technol.
,
11
(
7
), pp.
969
986
.
24.
Clifford
,
R. J.
,
Jones
,
T. V.
, and
Dunne
,
S. T.
,
1983
, “
Techniques for Obtaining Detailed Heat Transfer Coefficient Measurements Within Gas Turbine Blade and Vane Cooling Passages
,”
ASME Paper No. 83-GT-58
.
25.
Byerley
,
A. R.
,
Jones
,
T. V.
, and
Ireland
,
P. T.
,
1992
, “
Internal Cooling Passage Heat Transfer Near the Entrance to a Film Cooling Hole: Experimental and Computational Results
,”
ASME Paper No. 92-GT-241
.
26.
Munson
,
B. R.
,
Young
,
D. F.
, and
Okiishi
,
T. H.
,
2006
,
Fundamentals of Fluid Mechanics
, 5th ed.,
John Wiley and Sons
,
New York
,
405
406
.
27.
Ieronymidis
,
I.
,
Gillespie
,
D. R. H.
,
Ireland
,
P. T.
, and
Kingston
,
R.
,
2006
, “
The Use of High Blockage Ribs to Enhance Heat Transfer Coefficient Distributions in a Model of an Integrally Cast Cooling Manifold
,”
ASME Paper No. GT2006-91237
.
28.
Ryley
,
J. R.
,
McGilvray
,
M.
, and
Gillespie
,
D.
,
2019
, “
Local Heat Transfer Coefficient Measurements on an Engine-Representative Internal Cooling Passage
,”
J. Thermophys. Heat Trans.
,
33
(
1
), pp.
189
198
.
29.
McGilvray
,
M.
, and
Gillespie
,
D.
,
2011
,
Transient Heat Transfer Analysis Code for Liquid Crystal Experiments at the University of Oxford: Updated GUI Driven Software
,
University of Oxford
,
Oxford, UK
.
30.
Ireland
,
P. T.
,
Neely
,
A. J.
,
Gillespie
,
D. R. H.
, and
Robertson
,
A. J.
,
1999
, “
Turbulent Heat Transfer Measurements Using Liquid Crystals
,”
Int. J. Heat Fluid Flow
,
20
(
4
), pp.
355
367
.
31.
Tsang
,
C. L. P.
,
2002
, “
High Blockage Turbulators in Gas Turbine Cooling Passages
,”
Ph.D. dissertation
,
University of Oxford
,
Oxford, UK
.
32.
Byerley
,
A. R.
,
1989
, “
Heat Transfer Near the Entrance to a Film Cooling Hole in a Gas Turbine Blade
,”
Ph.D. dissertation
,
University of Oxford
,
Oxford, UK
.
33.
Moffat
,
R. J.
,
1982
, “
Contributions to the Theory of Single-Sample Uncertainty Analysis
,”
ASME J. Fluid Eng.
,
104
(
2
), pp.
250
260
.
34.
Menter
,
F. R.
,
1993
, “
Zonal Two Equation k-ω Turbulence Models for Aerodynamic Flows
,”
AIAA Paper No. 93-2906
.
35.
ANSYS
,
2016
,
ANSYS FLUENT® Release 17.1.0 Theory Guide
,
ANSYS, Inc.
,
Canonsburg, PA
.
36.
Dhopade
,
P.
,
Capone
,
L.
,
McGilvray
,
M.
,
Gillespie
,
D.
, and
Ireland
,
P.
,
2015
, “
Numerical Modelling Techniques for Turbine Blade Internal Cooling Passages
,”
ASME Paper No. GT2015-42393
.
37.
Taslim
,
M. E.
, and
Lengkong
,
A.
,
1998
, “
45 deg Round-Corner Rib Heat Transfer Coefficient Measurements in a Square Channel
,”
ASME Paper No. 98-GT-176
.
38.
Fiebig
,
M.
,
1995
, “
Embedded Vortices in Internal Flow: Heat Transfer and Pressure Loss Enhancement
,”
Int. J. Heat Fluid Flow
,
16
(
5
), pp.
376
388
.
39.
Fan
,
J. F.
,
Ding
,
W. K.
,
Zhang
,
J. F.
,
He
,
Y. L.
, and
Tao
,
W. Q.
,
2009
, “
A Performance Evaluation Plot of Enhanced Heat Transfer Techniques Oriented for Energy-Saving
,”
Int. J. Heat Mass Transfer
,
52
(
1–2
), pp.
33
44
.
40.
Kunstmann
,
S.
,
von Wolfersdorf
,
J.
, and
Ruedel
,
U.
,
2010
, “
Heat Transfer and Pressure Drop in Combustor Cooling Channels With Combinations of Geometrical Elements
,”
ASME Paper No. GT2010-23234
.
41.
Forsyth
,
P.
,
McGilvray
,
M.
, and
Gillespie
,
D. R. H.
,
2017
, “
Secondary Flow and Heat Transfer Coefficient Distributions in the Developing Flow Region of Ribbed Turbine Blade Cooling Passages
,”
Exp. Fluids
,
58
(
1
), pp.
1
15
.
42.
Iaccarino
,
G.
,
Ooi
,
A.
,
Durbin
,
P. A.
, and
Behnia
,
M.
,
2002
, “
Conjugate Heat Transfer Predictions in Two-Dimensional Ribbed Passages
,”
Int. J. Heat Fluid Flow
,
23
(
3
), pp.
340
345
.
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