Film cooling and sprayed thermal barrier coatings (TBCs) protect gas turbine components from the hot combustion gas temperatures. As gas turbine designers pursue higher turbine inlet temperatures, film cooling and TBCs are critical in protecting the durability of turbomachinery hardware. One obstacle to the synergy of these technologies is that TBC coatings can block cooling holes when applied to the components, causing a decrease in the film cooling flow area thereby reducing coolant flow for a given pressure ratio (PR). In this study, the effect of TBC blockages was simulated on film cooling holes for widely spaced cylindrical and shaped holes. At low blowing ratios for shaped holes, the blockages were found to have very little effect on adiabatic effectiveness. At high blowing ratios, the area-averaged effectiveness of shaped and cylindrical holes decreased as much as 75% from blockage. The decrease in area-averaged effectiveness was found to scale best with the effective momentum flux ratio of the jet exiting the film cooling hole for the shaped holes.

References

References
1.
Bunker
,
R. J.
,
2000
, “
Effect of Partial Coating Blockage on Film Cooling Effectiveness
,”
ASME
Paper No. 2000-GT-0244.10.1115/2000-GT-0244
2.
Bogard
,
D. G.
,
Schmidt
,
D. L.
, and
Tabbita
,
M.
,
1998
, “
Characterization and Laboratory Simulation of Turbine Airfoil Surface Roughness and Associated Heat Transfer
,”
ASME J. Turbomach.
,
120
(
2
), pp.
337
342
.10.1115/1.2841411
3.
Jovanovic
,
M. B.
,
de Lange
,
H. C.
, and
van Steenhoven
,
A. A.
,
2005
, “
Influence of Laser Drilling Imperfection on Film Cooling Performances
,”
ASME
Paper No. GT2005-68251.10.1115/GT2005-68251
4.
Demling
,
P.
, and
Bogard
,
D. G.
,
2006
, “
The Effects of Obstructions on Film Cooling Effectiveness on the Suction Side of a Gas Turbine Vane
,”
ASME
Paper No. GT2006-90577.10.115/GT2006-90577
5.
Sundaram
,
N.
, and
Thole
,
K. A.
,
2007
, “
Effects of Surface Deposition, Hole Blockage, and Thermal Barrier Coating Spallation on Vane Endwall Film Cooling
,”
ASME J. Turbomach.
,
129
(
3
), pp.
599
607
.10.1115/1.2720485
6.
Na
,
S.
,
Cunha
,
F. J.
,
Chyu
,
M. K.
, and
Shih
,
T. I.-P.
,
2006
, “
Effects of Coating Blockage and Deposit on Film-Cooling Effectiveness and Surface Heat Transfer
,”
AIAA
Paper No. 2006-0024.10.2514/6.2006-24
7.
Eberly
,
M. K.
, and
Thole
,
K. A.
,
2014
, “
Time-Resolved Film-Cooling Flows at High and Low Density Ratios
,”
ASME J. Turbomach.
,
136
(
6
), p.
061003
.10.1115/1.4025574
8.
Schroeder
,
R. P.
, and
Thole
,
K. A.
,
2013
, “
Shaped Hole Literature Review Database
,”
Penn State Experimental and Computational Convection Laboratory (ExCCL), University Park, PA
, avaiilable at: http://www.mne.psu.edu/psuturbine/
9.
Schroeder
,
R. P.
, and
Thole
,
K. A.
,
2014
, “
Adiabatic Effectiveness Measurements for a Baseline Shaped Film Cooling Hole
,”
ASME
Paper No. GT2014-25992.10.1115/GT2014-25992
10.
Thole
,
K. A.
,
Sinha
,
A. K.
,
Bogard
,
D. G.
, and
Crawford
,
M. E.
,
1992
, “
Mean Temperature Measurements of Jets With a Crossflow for Gas Turbine Film Cooling Application
,”
Rotating Machinery Transport Phenomena
,
J. H.
Kim
, and
W. J.
Yang
, eds.,
Hemisphere
,
New York
.
11.
Sinha
,
A. K.
,
Bogard
,
D. G.
, and
Crawford
,
M. E.
,
1991
, “
Film Cooling Effectiveness Downstream of a Single Row of Holes With Variable Density Ratio
,”
ASME J. Turbomach.
,
113
(
3
), pp.
442
449
.10.1115/1.2927894
12.
Figliola
,
R. S.
, and
Beasley
,
D. E.
,
2006
,
Theory and Design for Mechanical Measurements
,
Wiley
,
Hoboken, NJ
.
13.
Burd
,
S. W.
, and
Simon
,
T. W.
,
1999
, “
Measurements of Discharge Coefficients in Film Cooling
,”
ASME J. Turbomach.
,
121
(
2
), pp.
243
248
.10.1115/1.2841307
14.
Demling
,
P. D. R.
,
2005
, “
The Effects of Obstructions on Film Cooling Effectiveness on the Suction Side of a Gas Turbine Vane
,” Master's thesis, The University of Texas at Austin, Austin, TX.
You do not currently have access to this content.