Abstract

The objective of this study is to determine the differences in flow fields between the 30 deg in-line and staggered arrangements of teardrop-shaped dimples, and to explain why the surface-averaged Nusselt number with the 30 deg in-line arrangement was 28.7% higher than that with the 30 deg staggered arrangement in our previous study. Measurements of the instantaneous velocity fields over the dimpled cutback surfaces in the two arrangements were performed at five spanwise cross sections using two-dimensional three-component particle tracking velocimetry (2D3C-PTV). Recirculation flows were observed only inside the dimples in the in-line arrangement, and the region above the recirculation flows exhibited a higher Reynolds shear stress. In this region, turbulent mixing between the high-speed cooling-flow and the low-speed recirculation-flow can be promoted. Streamlines of the time-averaged velocities showed that approximately half the fluid flowing out of a teardrop-shaped dimple in the in-line arrangement hardly flowed into the ones downstream. The remainder of the fluid mostly flowed into the dimple immediately downstream, and the inflow of the fluid into further downstream dimples decreased gradually. From the PTV results, we can deduce that the fluid motions in the in-line arrangement leads to a larger temperature-difference between the dimple wall and the fluid because the inflow of fluid heated inside upstream dimples into the downstream ones is less than in the staggered arrangement. Consequently, the Nusselt number in the in-line arrangement was higher.

References

1.
Cunha
,
F. J.
, and
Chyu
,
M. K.
,
2006
, “
Trailing-Edge Cooling for Gas Turbines
,”
J. Propul. Power
,
22
(
2
), pp.
286
300
.10.2514/1.20898
2.
Taslim
,
M. E.
,
Spring
,
S. D.
, and
Mehlman
,
B. P.
,
1992
, “
An Experimental Investigation of Film Cooling Effectiveness for Slots of Various Exit Geometries
,”
J. Thermophys. Heat Trans.
,
6
(
2
), pp.
302
307
.10.2514/3.359
3.
Martini
,
P.
,
Schulz
,
A.
,
Bauer
,
H.-J.
, and
Whitney
,
C. F.
,
2006
, “
Detached Eddy Simulation of Film Cooling Performance on the Trailing Edge Cutback of Gas Turbine Airfoils
,”
ASME J. Turbomach.
,
128
(
2
), pp.
292
299
.10.1115/1.2137739
4.
Effendy
,
M.
,
Yao
,
Y. F.
,
Yao
,
J.
, and
Marchant
,
D. R.
,
2016
, “
DES Study of Blade Trailing Edge Cutback Cooling Performance With Various Lip Thicknesses
,”
Appl. Therm. Eng.
,
99
(
25
), pp.
434
445
.10.1016/j.applthermaleng.2015.11.103
5.
Schneider
,
H.
,
Von Terzi
,
D.
, and
Bauer
,
H. J.
,
2012
, “
Turbulent Heat Transfer and Large Coherent Structures in Trailing-Edge Cutback Film Cooling
,”
Flow Turbul. Combust.
,
88
(
1–2
), pp.
101
120
.10.1007/s10494-011-9379-3
6.
Horback
,
T.
,
Schulz
,
A.
, and
Bauer
,
H.-J.
,
2010
, “
Trailing Edge Film Cooling of Gas Turbine Airfoils–External Cooling Performance of Various Internal Pin Fin Configurations
,”
ASME
Paper No. GT2010-23578.10.1115/GT2010-23578
7.
Yang
,
Z.
, and
Hu
,
H.
,
2012
, “
An Experimental Investigation on the Trailing Edge Cooling of Turbine Blades
,”
Propul. Power Res.
,
1
(
1
), pp.
36
47
.10.1016/j.jppr.2012.10.007
8.
Ling
,
J.
,
Elkins
,
C. J.
, and
Eaton
,
J. K.
,
2014
, “
The Effect of Land Taper Angle on Trailing Edge Slot Film Cooling
,”
ASME
Paper No. GT2014-25579.10.1115/GT2014-25579
9.
Elkins
,
C. J.
,
Markl
,
M.
,
Pelc
,
N.
, and
Eaton
,
J. K.
,
2003
, “
4D Magnetic Resonance Velocimetry for Mean Velocity Measurements in Complex Turbulent Flows
,”
Exp. Fluids
,
34
(
4
), pp.
494
503
.10.1007/s00348-003-0587-z
10.
Murata
,
A.
,
Nishida
,
S.
,
Saito
,
H.
,
Iwamoto
,
K.
,
Okita
,
Y.
, and
Nakamata
,
C.
,
2012
, “
Effects of Surface Geometry on Film Cooling Performance at Airfoil Trailing Edge
,”
ASME J. Turbomach.
,
134
(
5
), p.
051033
.10.1115/1.4004828
11.
Nishida
,
S.
,
Murata
,
A.
,
Ito
,
K.
,
Saito
,
H.
,
Iwamoto
,
K.
,
Okita
,
Y.
, and
Nakamata
,
C.
,
2011
, “
Film Cooling Performance Over Dimpled Cutback Surface at Airfoil Trailing Edge
,”
ASME
Paper No. IGTC2011-0195.10.1115/IGTC2011-0195
12.
Chyu
,
M. K.
,
Yu
,
Y.
, and
Ding
,
H.
,
1999
, “
Heat Transfer Enhancement in Rectangular Channels With Concavities
,”
J. Enhanced Heat Transfer
,
6
(
6
), pp.
429
439
.10.1615/JEnhHeatTransf.v6.i6.40
13.
Rao
,
Y.
,
Li
,
B.
, and
Feng
,
Y.
,
2015
, “
Heat Transfer of Turbulent Flow Over Surfaces With Spherical Dimples and Teardrop Dimples
,”
J. Exp. Therm. Fluid Sci.
,
61
, pp.
201
209
.10.1016/j.expthermflusci.2014.10.030
14.
Rao
,
Y.
,
Feng
,
Y.
,
Li
,
B.
, and
Weigand
,
B.
,
2015
, “
Experimental and Numerical Study of Heat Transfer and Flow Friction in Channels With Dimples of Different Shapes
,”
ASME J. Heat Transfer
,
137
(
3
), p.
031901
.10.1115/1.4029036
15.
Yoon
,
H. S.
,
Park
,
S. H.
,
Choi
,
C.
, and
Ha
,
M. Y.
,
2015
, “
Numerical Study on Characteristics of Flow and Heat Transfer in a Cooling Passage With a Tear-Drop Dimple Surface
,”
Int. J. Therm. Sci.
,
89
, pp.
121
135
.10.1016/j.ijthermalsci.2014.11.002
16.
Yano
,
K.
,
Murata
,
A.
,
Sekijima
,
M.
,
Saito
,
H.
, and
Iwamoto
,
K.
,
2015
, “
Effects of Dimpled-Cutback-Surface Rotation Angle on Film Cooling Performance at Airfoil Trailing Edge
,”
Proceedings of International Gas Turbine Congress
,
Tokyo, Japan
, Nov. 15–20, Paper No. IGTC2015-0032.
17.
Murata
,
A.
,
Yano
,
H.
,
Hanai
,
M.
,
Saito
,
H.
, and
Iwamoto
,
K.
,
2017
, “
Arrangement Effects of Inclined Teardrop-Shaped Dimples on Film Cooling Performance of Dimpled Cutback Surface at Airfoil Trailing Edge
,”
Int. J. Heat Mass Transfer
,
107
, pp.
761
770
.10.1016/j.ijheatmasstransfer.2016.11.081
18.
Murata
,
A.
,
Mori
,
E.
, and
Iwamoto
,
K.
,
2014
, “
Effects of Surface Geometry and Blowing Ratio on Film Cooling Performance at Airfoil Trailing Edge Investigated by Using Large Eddy Simulation
,”
Proceedings of 15th International Heat Transfer Conference
,
Kyoto, Japan
, Aug. 10–15, pp.
3399
3413
.
19.
Murata
,
A.
,
Hanai
,
M.
,
Tokutake
,
T.
,
Saito
,
H.
, and
Iwamoto
,
K.
,
2015
, “
Three-Component PTV Measurements of Film Cooling Flow in Multiple Planes Over Cutback Surface With Inclined Teardrop-Shaped Dimples at Airfoil Trailing Edge
,”
Proceedings of International Gas Turbine Congress
,
Tokyo, Japan
, Nov. 15–20, Paper No. IGTC2015-0039.
20.
Murai
,
S.
,
Okuda
,
T.
, and
Nakamura
,
H.
,
1981
, “
A Study on Analytical Photogrammetry With Use of Non-Metric Camera
,” Report of the Institute of Industrial Science,
The University of Tokyo
,
Tokyo, Japan
, 29(6), pp. 1–15 (in Japanese).
21.
Ninomiya
,
N.
,
Akiyama
,
M.
, and
Sugiyama
,
H.
,
1995
, “
3-D PTV Velocity Measurement Applied to the Flow in a Complex Flow Geometry
,”
J. Visualization Soc. Jpn.
,
15
(
59
), pp.
279
284
(in Japanese).10.3154/jvs.15.59_279
22.
Hassan
,
Y. A.
, and
Canaan
,
R. E.
,
1991
, “
Full-Field Bubbly Flow Velocity Measurements Using a Multiframe Particle Tracking Technique
,”
Exp. Fluids
,
12
(1–2), pp.
49
60
.10.1007/BF00226565
23.
ANSI/ASME
,
1985
, “
Measurement Uncertainty
,”
American Society of Mechanical Engineering
,
New York
, Standard No.
ANSI/ASME PTC 19.1
.
24.
Kays
,
W.
, and
Crawford
,
M.
,
1993
,
Convective Heat and Mass Transfer
, 3rd ed.,
McGraw-Hill
,
New York
, p.
316
.
25.
Zhou
,
W.
,
Rao
,
Y.
, and
Hu
,
H.
,
2016
, “
An Experimental Investigation on the Characteristics of Turbulent Boundary Layer Flows Over a Dimpled Surface
,”
ASME J. Fluid. Eng.
,
138
(
2
), p.
021204
.10.1115/1.4031260
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