In internal cooling passages in a turbine blade, rib structures are widely applied to augment convective heat transfer by the coolant passing through over the ribbed surfaces. This study concentrates on perforated 90 deg ribs with inclined holes in a cooling duct with rectangular cross section, aiming at improving the perforated holes with additional secondary flows caused by inclined hole arrangements. Two sets of perforated ribs are used in the experiments with the inclined angle of the holes changing from 0 deg to 45 deg and the cross section are, respectively, circular and square. Steady-state liquid crystal thermography (LCT) is applied to measure the ribbed surface temperature and obtain corresponding convective heat transfer coefficients (HTCs). Two turbulence models, i.e., the kω shear stress transportation (SST) model and the detached eddy simulation (DES) model, are used in the numerical studies to simulate the flow fields. All the inclined cases have slightly larger overall averaged Nusselt number (Nu) than with straight cases. The enhancement ratio is approximately 1.85–4.94%. The averaged Nu in the half portion against the inclined direction is enlarged for the inclined hole cases. The inclined hole cases usually have smaller averaged Nu in the half portion along the inclined direction. For the straight hole case and small inclined angle case, the penetrated flows mix with the mainstream flows at the perforated regions. When the inclined angle is larger, the penetrated flows are pushed to the inclined direction and mixing with the approaching flows occurs just at the side of the inclined direction.

References

References
1.
Han
,
J. C.
, and
Park
,
J. S.
,
1988
, “
Developing Heat Transfer in Rectangular Channels With Rib Turbulators
,”
Int. J. Heat Mass Transf.
,
31
(
1
), pp.
183
195
.
2.
Liou
,
T. M.
, and
Hwang
,
J. J.
,
1993
, “
Effect of Ridge Shapes on Turbulent Heat Transfer and Friction in a Rectangular Channel
,”
Int. J. Heat Mass Transf.
,
36
(
4
), pp.
931
940
.
3.
Han
,
J. C.
,
Dutta
,
S.
, and
Ekkad
,
S.
,
2012
,
Gas Turbine Heat Transfer and Cooling Technology
,
CRC Press
, Boca Raton, FL.
4.
Alfarawi
,
S.
,
Abdel-Moneim
,
S.
, and
Bodalal
,
A.
,
2017
, “
Experimental Investigations of Heat Transfer Enhancement From Rectangular Duct Roughened by Hybrid Ribs
,”
Int. J. Therm. Sci.
,
118
, pp.
123
138
.
5.
Abraham
,
S.
, and
Vedula
,
R. P.
,
2016
, “
Heat Transfer and Pressure Drop Measurements in a Square Cross-Section Converging Channel With V and W Rib Turbulators
,”
Exp. Therm. Fluid Sci.
,
70
, pp.
208
219
.
6.
Singh
,
P.
,
Pandit
,
J.
, and
Ekkad
,
S. V.
,
2017
, “
Characterization of Heat Transfer Enhancement and Frictional Losses in a Two-Pass Square Duct Featuring Unique Combinations of Rib Turbulators and Cylindrical Dimples
,”
Int. J. Heat Mass Transf.
,
106
, pp.
629
647
.
7.
Singh
,
P.
, and
Ekkad
,
S. V.
,
2017
, “
Experimental Study of Heat Transfer Augmentation in a Two-Pass Channel Featuring V-Shaped Ribs and Cylindrical Dimples
,”
Appl. Therm. Eng.
,
116
, pp.
205
216
.
8.
Liou
,
T. M.
,
Chang
,
S. W.
,
Lan
,
Y. A.
,
Chan
,
S. P.
, and
Liu
,
Y. S.
,
2017
, “
Heat Transfer and Flow Characteristics of Two-Pass Parallelogram Channels With Attached and Detached Transverse Ribs
,”
ASME J. Heat Transfer
,
139
(
4
), p.
042001
.
9.
Kumar
,
A.
,
Chauhan
,
R.
,
Kumar
,
R.
,
Singh
,
T.
,
Sethi
,
M.
, and
Sharma
,
A.
,
2017
, “
Developing Heat Transfer and Pressure Loss in an Air Passage With Multi Discrete V-Blockages
,”
Exp. Therm. Fluid Sci.
,
84
, pp.
266
278
.
10.
Liu
,
J.
,
Hussain
,
S.
,
Wang
,
J.
,
Wang
,
L.
,
Xie
,
G.
, and
Sundén
,
B.
,
2018
, “
Heat Transfer Enhancement and Turbulent Flow in a High Aspect Ratio Channel (4: 1) With Ribs of Various Truncation Types and Arrangements
,”
Int. J. Therm. Sci.
,
123
, pp.
99
116
.
11.
Liu
,
J.
,
Wang
,
J.
,
Hussain
,
S.
,
Wang
,
L.
,
Xie
,
G.
, and
Sundén
,
B.
,
2018
, “
Application of Fractal Theory in the Arrangement of Truncated Ribs in a Rectangular Cooling Channel (4: 1) of a Turbine Blade
,”
Appl. Therm. Eng.
,
139
, pp.
488
505
.
12.
Liou
,
T. M.
, and
Chen
,
S. H.
,
1998
, “
Turbulent Heat and Fluid Flow in a Passage Disturbed by Detached Perforated Ribs of Different Heights
,”
Int. J. Heat Mass Transf.
,
41
(
12
), pp.
1795
1806
.
13.
Kukreja
,
R.
, and
Lau
,
S.
,
1998
, “
Distributions of Local Heat Transfer Coefficient on Surfaces With Solid and Perforated Ribs
,”
J. Enhanced Heat Transfer
,
5
(
1
), pp. 9–21.
14.
Sara
,
O.
,
Pekdemir
,
T.
,
Yapici
,
S.
, and
Yilmaz
,
M.
,
2001
, “
Heat-Transfer Enhancement in a Channel Flow With Perforated Rectangular Blocks
,”
Int. J. Heat Fluid Flow
,
22
(
5
), pp.
509
518
.
15.
Buchlin
,
J. M.
,
2002
, “
Convective Heat Transfer in a Channel With Perforated Ribs
,”
Int. J. Therm. Sci.
,
41
(
4
), pp.
332
340
.
16.
Sahel
,
D.
,
Ameur
,
H.
,
Benzeguir
,
R.
, and
Kamla
,
Y.
,
2016
, “
Enhancement of Heat Transfer in a Rectangular Channel With Perforated Baffles
,”
Appl. Therm. Eng.
,
101
, pp.
156
164
.
17.
Hasanpour
,
A.
,
Farhadi
,
M.
, and
Sedighi
,
K.
,
2016
, “
Experimental Heat Transfer and Pressure Drop Study on Typical, Perforated, V-Cut and U-Cut Twisted Tapes in a Helically Corrugated Heat Exchanger
,”
Int. Commun. Heat Mass Transfer
,
71
, pp.
126
136
.
18.
Kumar
,
R.
,
Kumar
,
A.
,
Chauhan
,
R.
, and
Maithani
,
R.
,
2018
, “
Comparative Study of Effect of Various Blockage Arrangements on Thermal Hydraulic Performance in a Roughened Air Passage
,”
Renewable Sustainable Energy Rev.
,
81
, pp.
447
463
.
19.
Saidi
,
A.
, and
Sunden
,
B.
,
2000
, “
Numerical Simulation of Turbulent Convective Heat Transfer in Square Ribbed Ducts
,”
Numer. Heat Transfer: Part A
,
38
(
1
), pp.
67
88
.
20.
Lin
,
Y. L.
,
Shih
,
T. P.
,
Stephens
,
M.
, and
Chyu
,
M.
,
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
(
2
), pp.
219
232
.
21.
Wongcharee
,
K.
,
Changcharoen
,
W.
, and
Eiamsa-ard
,
S.
,
2011
, “
Numerical Investigation of Flow Friction and Heat Transfer in a Channel With Various Shaped Ribs Mounted on Two Opposite Ribbed Walls
,”
Int. J. Chem. Reactor Eng.
,
9
(
1
), pp. 1–22.
22.
Gao
,
T.
,
Zhu
,
J.
,
Liu
,
C.
, and
Xu
,
J.
,
2016
, “
Numerical Study of Conjugate Heat Transfer of Steam and Air in High Aspect Ratio Rectangular Ribbed Cooling Channel
,”
J. Mech. Sci. Technol.
,
30
(
3
), pp.
1431
1442
.
23.
Kim
,
D. H.
,
Lee
,
B. J.
,
Park
,
J. S.
,
Kwak
,
J. S.
, and
Chung
,
J. T.
,
2016
, “
Effects of Inlet Velocity Profile on Flow and Heat Transfer in the Entrance Region of a Ribbed Channel
,”
Int. J. Heat Mass Transf.
,
92
, pp.
838
849
.
24.
Marocco
,
L.
, and
Franco
,
A.
,
2017
, “
Direct Numerical Simulation and RANS Comparison of Turbulent Convective Heat Transfer in a Staggered Ribbed Channel With High Blockage
,”
ASME J. Heat Transfer
,
139
(
2
), p.
021701
.
25.
Ravi
,
B. V.
,
Singh
,
P.
, and
Ekkad
,
S. V.
,
2017
, “
Numerical Investigation of Turbulent Flow and Heat Transfer in Two-Pass Ribbed Channels
,”
Int. J. Therm. Sci.
,
112
, pp.
31
43
.
26.
Wang
,
N.
,
Chen
,
A. F.
,
Zhang
,
M.
, and
Han
,
J. C.
,
2018
, “
Turbine Blade Leading Edge Cooling With One Row of Normal or Tangential Impinging Jets
,”
ASME J. Heat Transfer
,
140
(
6
), p.
062201
.
27.
Spalart
,
P.
,
Jou
,
W.
,
Strelets
,
M.
, and
Allmaras
,
S.
,
1997
, “
Comments on the Feasibility of LES for Wings, and on a Hybrid RANS/LES Approach
,”
Adv. DNS/LES
,
1
, pp.
4
8
.
28.
Sagaut
,
P.
,
2006
,
Large Eddy Simulation for Incompressible Flows: An Introduction
,
Springer Science & Business Media
, Berlin.
29.
Gritskevich
,
M. S.
,
Garbaruk
,
A. V.
,
Schütze
,
J.
, and
Menter
,
F. R.
,
2012
, “
Development of DDES and IDDES Formulations for the k–ω Shear Stress Transport Model
,”
Flow, Turbul. Combust.
,
88
(
3
), pp.
431
449
.
30.
Shur
,
M. L.
,
Spalart
,
P. R.
,
Strelets
,
M. K.
, and
Travin
,
A. K.
,
2008
, “
A Hybrid RANS-LES Approach With Delayed-DES and Wall-Modelled LES Capabilities
,”
Int. J. Heat Fluid Flow
,
29
(
6
), pp.
1638
1649
.
31.
Singh
,
P.
,
Ravi
,
B. V.
, and
Ekkad
,
S. V.
,
2016
, “
Experimental and Numerical Study of Heat Transfer Due to Developing Flow in a Two-Pass Rib Roughened Square Duct
,”
Int. J. Heat Mass Transf.
,
102
, pp.
1245
1256
.
32.
Azad
,
G. S.
,
Uddin
,
M. J.
,
Han
,
J.-C.
,
Moon
,
H. K.
, and
Glezer
,
B.
, 2002, “
Heat Transfer in a Two-Pass Rectangular Rotating Channel With 45-Deg Angled Rib Turbulators
,”
ASME J. Turbomach.
,
124
(2), pp. 251–259.
33.
Kaewchoothong
,
N.
,
Maliwan
,
K.
,
Takeishi
,
K.
, and
Nuntadusit
,
C.
,
2017
, “
Effect of Inclined Ribs on Heat Transfer Coefficient in Stationary Square Channel
,”
Theor. Appl. Mech. Lett.
,
7
(
6
), pp.
344
350
.
34.
Wang
,
C.
,
2016
, “
Experimental Study of Outlet Guide Vane Heat Transfer and Gas Turbine Internal Cooling
,” Ph.D. thesis, Lund University, Lund, Skane, Sweden.
35.
Moffat
,
R. J.
,
1988
, “
Describing the Uncertainties in Experimental Results
,”
Exp. Therm. Fluid Sci.
,
1
(
1
), pp.
3
17
.
36.
Menter
,
F. R.
,
1994
, “
Two-Equation Eddy-Viscosity Turbulence Models for Engineering Applications
,”
AIAA J.
,
32
(
8
), pp.
1598
1605
.
37.
Menter
,
F.
,
Ferreira
,
J. C.
,
Esch
,
T.
,
Konno
,
B.
, and
Germany
,
A.
, 2003, “
The SST Turbulence Model With Improved Wall Treatment for Heat Transfer Predictions in Gas Turbines
,”
International Gas Turbine Congress
, Tokyo, Japan, pp. 1–7.
38.
Jeong
,
J.
, and
Hussain
,
F.
,
1995
, “
On the Identification of a Vortex
,”
J. Fluid Mech.
,
285
(
1
), pp.
69
94
.
39.
Haller
,
G.
,
2005
, “
An Objective Definition of a Vortex
,”
J. Fluid Mech.
,
525
, pp.
1
26
.
You do not currently have access to this content.