The trailing edge section of modern high-pressure turbine airfoils is an area that requires a high degree of attention from turbine performance and durability standpoints. Aerodynamic loss near the trailing edge includes expansion waves, normal shocks, and wake shedding. Thermal issues associated with trailing edge are also very complex and challenging. To maintain effective cooling ensuring metal temperature below design limit is particularly difficult, as it needs to be implemented in a relatively small area of the airfoil. To date, little effort has been devoted to advancing the fundamental understanding of the thermal characteristics in airfoil trailing edge regions. Described in this paper are the procedures leading to closed-form, analytical solutions for temperature profile for four most representative trailing edge configurations. The configurations studied are: (1) solid wedge shape without discharge, (2) wedge with slot discharge, (3) wedge with discrete-hole discharge, and (4) wedge with pressure-side cutback slot discharge. Comparison among these four cases is made primarily in the context of airfoil metal temperature and resulting cooling effectiveness. Further discussed in the paper are the overall and detail design parameters for preferred trailing edge cooling configurations as they affect turbine airfoil performance and durability.

1.
Kuhne
,
C. M.
, 2003, “
Reduced Shock Transonic Airfoil
,” US Patent No. 2003/0072649A1, April.
2.
Eisemann
,
K. M.
, 2003, “
Uncooled Data Reduction
,”
Pratt & Whitney Internal Documentation
,
Pratt & Whitney
, East Hartford, CT.
3.
Karamcheti
,
K.
, 1980,
Principles of Ideal-Fluid Aerodynamics
,
R. E. Krieger Pub.
,
Malabor, FL
, Chap. 13.
4.
Maclachlan
,
D. W.
, and
Knowles
,
D. M.
, 2002, “
The Effect of Material on the Analysis of Single Crystal Turbine Blades: Part I-Material Model
,”
Fatigue and Fracture Engineering Material Science 25
,
Blackwell Science Ltd.
,
Oxford
, pp.
385
398
.
5.
Maclachlan
,
D. W.
, and
Knowles
,
D. M.
, 2002, “
The Effect of Material on the Analysis of Single Crystal Turbine Blades: Part II-Component Analysis
,”
Fatigue and Fracture Engineering Material Science 25
,
Blackwell Science Ltd.
,
Oxford
, pp.
385
398
.
6.
Langston
,
L.
, 2004, “
A Year of Turbulence
,”
Power and Energy
,
6
, pp.
29
33
.
7.
Cunha
,
F. J.
, 1994, “
Integrated Steam/Gas Cooling System for Gas Turbines
,” US Patent No. 5,340,274, August.
8.
Jacala
,
A.
,
Davis
,
R. M.
,
Sullivan
,
M. A.
,
Chyu
,
R. P.
, and
Staub
,
F.
, 1996, “
Closed Circuit Steam Cooled Bucket
,” US Patent No. 5,536,143, July.
9.
Cunha
,
F. J.
,
DeAngelis
,
D. A.
,
Brown
,
T. A.
,
Chopra
,
S.
,
Correia
,
V. H. S.
, and
Predmore
,
D. R.
, 1997, “
Turbine Stator Vane Segments Having Combined Air and Steam Cooling Circuits
,” US Patent No. 5,634,766.
10.
Lee
,
C.-P.
, 2001, “
Turbine Blade Trailing Edge Cooling Openings and Slots
,” US Patent No. 6,174,135B1, Jan. 16.
11.
Cunha
,
F. J.
,
Dahmer
,
M. T.
, and
Chyu
,
M. K.
, 2005, “
Thermal-Mechanical Life Prediction System for Anisotropic Turbine Components
,” ASME Paper No. GT2005-68107.
12.
Braddy
,
B. T.
, 1981, “
Film Cooled Airfoil Body
,” US Patent No. 4,303,374, Dec.
13.
Starkweather
,
J. H.
, 1998, “
Turbine Blade
,” US Patent No. 5,813,836, Sept.
14.
Manning
,
R. F.
,
Acquaviva
,
P. J.
, and
Demers
,
E.
, 1981, “
Series Impingement Cooled Airfoil
,” US Patent No. 6036441.
15.
Cunha
,
F. J.
, and
DeAngelis
,
D. A.
, 2000, “
Cooling Circuits for Trailing Edge Cavities in Airfoils
,” US Patent No. 6,056,505, May.
16.
Hill
,
E. C.
,
Liang
,
G. P.
, and
Auxier
,
T.
, 1986, “
Airfoil Trailing Edge Cooling Arrangement
,” US Patent No. 4,601,638, July.
17.
Chyu
,
M. K.
,
Uysal
,
U.
, and
Li
,
P.-W.
, 2002, “
Convective Heat Transfer in a Triple-Cavity Structure Near Turbine Blade Trailing Edge
,” ASME Paper No. IMECE2002-32405.
18.
Zukauskas
,
A. A.
, 1972, “
Heat Transfer from Tubes in Cross Flow
,”
Adv. Heat Transfer
0065-2717,
8
, pp.
116
133
.
19.
Ishida
,
K.
, and
Hamabe
,
K.
, 1985, “
Effect of Pin-Fin Aspect Ratio and Arrangement on Heat Transfer and Pressure Drop of Pin Fin Duct for Airfoil Internal Cooling Passage
,” ASME Paper No. 85-WA/HT-62.
20.
Han
,
J. C.
,
Dutta
,
S.
, and
Ekkad
,
S.
, 2000,
Gas Turbine Heat Transfer and Cooling Technology
,
1st ed.
,
Taylor and Francis
,
New York
, Chap. 1.
21.
Chyu
,
M. K.
, 1990, “
Heat Transfer and Pressure Drop for Short Pin-Fin Arrays With Pin-Endwall Fillet
,”
ASME J. Heat Transfer
0022-1481,
112
, pp.
926
932
.
22.
Eckert
,
E. R. G.
, 1976, “
Analogies to Heat Transfer Processes
,”
Measurements in Heat Transfer
,
E. R. G.
Eckert
and
R. J.
Goldstein
, eds.,
Hemisphere Publishing Corp.
,
New York
, Chap. 1.
23.
Goldstein
,
R. J.
, 1976, “
Film Cooling
,”
Adv. Heat Transfer
0065-2717,
7
, pp.
357
358
.
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