It is necessary to understand how film cooling influences the external convective boundary condition involving both the adiabatic wall temperature and the heat transfer coefficient in order to predict the thermal durability of a gas turbine hot gas path component. Most studies in the past have considered only steady flow, but studies of the unsteadiness naturally present in turbine flow have become more prevalent. One source of unsteadiness is wake passage from upstream components which can cause fluctuations in the stagnation location on turbine airfoils. This in turn causes unsteadiness in the behavior of the leading edge coolant jets and thus fluctuations in both the adiabatic effectiveness and heat transfer coefficient. The dynamics of h and η are now quantifiable with modern inverse heat transfer methods and nonintrusive infrared thermography. The present study involved the application of a novel inverse heat transfer methodology to determine time-resolved adiabatic effectiveness and heat transfer coefficient waveforms on a simulated turbine blade leading edge with an oscillating stagnation position. The leading edge geometry was simulated with a circular cylinder with a coolant hole located 21.5 deg downstream from the leading edge stagnation line, angled 20 deg to the surface and 90 deg to the streamwise direction. The coolant plume is shown to shift in response to the stagnation line movement. These oscillations thus influence the film cooling coverage, and the time-averaged benefit of film cooling is influenced by the oscillation.

References

References
1.
Sen
,
B.
,
Schmidt
,
D. L.
, and
Bogard
,
D. G.
,
1996
, “
Film Cooling With Compound Angle Holes: Heat Transfer
,”
ASME J. Turbomach.
,
118
(
4
), pp.
800
806
.
2.
Vedula
,
R. P.
, and
Metzger
,
D. E.
,
1991
, “
A Method for the Simultaneous Determination of Local Effectiveness and Heat Transfer Distributions in Three Temperature Convective Situations
,”
ASME
Paper No. 91-GT-345.
3.
Ekkad
,
S. V.
,
Ou
,
S.
, and
Rivir
,
R. B.
,
2004
, “
A Transient Infrared Thermography Method for Simultaneous Film Cooling Effectiveness and Heat Transfer Coefficient Measurements From a Single Test
,”
ASME J. Turbomach.
,
126
(
4
), pp.
597
603
.
4.
Incropera
,
F.
, and
DeWitt
,
D.
,
1996
,
Fundamentals of Heat and Mass Transfer
,
4th ed.
,
Wiley
,
Hoboken, NJ
.
5.
Abhari
,
R. S.
,
1996
, “
Impact of Rotor–Stator Interaction on Turbine Blade Film Cooling
,”
ASME J. Turbomach.
,
118
(
1
), pp.
123
133
.
6.
Ligrani
,
P. M.
,
Gong
,
R.
, and
Cuthrell
,
J. M.
,
1997
, “
Bulk Flow Pulsation and Film Cooling: Flow Structure Just Downstream of Holes
,”
ASME J. Turbomach.
,
119
(
3
), pp.
568
573
.
7.
Rutledge
,
J. L.
, and
McCall
,
J. F.
,
2013
, “
Determination of Time-Resolved Heat Transfer Coefficient and Adiabatic Effectiveness Waveforms With Unsteady Film Cooling
,”
ASME J. Turbomach.
,
135
, p.
021021
.
8.
Rutledge
,
J. L.
,
2013
, “
Heat Transfer Boundary Condition Waveforms on a Turbine Blade Leading Edge With Unsteady Film Cooling
,”
ASME
Paper No. GT2013-94587.
9.
Hanford
,
A. J.
, and
Wilson
,
D. E.
,
1994
, “
The Effect of a Turbulent Wake on the Stagnation Point: Part II—Heat Transfer Results
,”
ASME J. Turbomach.
,
116
(
1
), pp.
46
56
.
10.
Johnson
,
R.
,
Maikell
,
J.
,
Bogard
,
D.
,
Piggush
,
J.
,
Kohli
,
A.
, and
Blair
,
M.
,
2009
, “
Experimental Study of the Effects of an Oscillating Approach Flow on Overall Cooling Performance of a Simulated Turbine Blade Leading Edge
,”
ASME
Paper No. GT2009-60290.
11.
Johnson
,
R. G.
,
2008
, “
Experimental Study of the Effect of Oscillating Stagnation Line on Overall Cooling Performance on a Leading Edge With One Row of Cooling Holes
,” M.S. thesis, University of Texas at Austin, Austin, TX.
12.
Dullenkopf
,
K.
,
Schulz
,
A.
, and
Wittig
,
S.
,
1991
, “
The Effect of Incident Wake Conditions of the Mean Heat Transfer of an Airfoil
,”
ASME J. Turbomach.
,
113
(
3
), pp.
412
418
.
13.
Mick
,
W. J.
, and
Mayle
,
R. E.
,
1988
, “
Stagnation Film Cooling and Heat Transfer, Including Its Effect Within the Hole Pattern
,”
ASME J. Turbomach.
,
110
(
1
), pp.
66
72
.
14.
Mehendale
,
A. B.
, and
Han
,
J. C.
,
1992
, “
Influence of High Mainstream Turbulence on Leading Edge Film Cooling Heat Transfer
,”
ASME J. Turbomach.
,
114
(
4
), pp.
707
715
.
15.
Du
,
H.
,
Ekkad
,
S. V.
, and
Han
,
J. C.
,
1997
, “
Effect of Unsteady Wake With Trailing Edge Coolant Ejection on Detailed Heat Transfer Coefficient Distributions for a Gas Turbine Blade
,”
ASME J. Turbomach.
,
119
(2), pp.
242
248
.
16.
Pietrzyk
,
J. R.
,
Bogard
,
D. G.
, and
Crawford
,
M. E.
,
1990
, “
Effects of Density Ratio on the Hydrodynamics of Film Cooling
,”
ASME J. Turbomach.
,
112
(
3
), pp.
437
443
.
17.
Sinha
,
A. K.
,
Bogard
,
D. G.
, and
Crawford
,
M. E.
,
1991
, “
Film Cooling Downstream of a Single Row of Holes With Variable Density Ratio
,”
ASME J. Turbomach.
,
113
(
3
), pp.
442
449
.
18.
Eberly
,
M. K.
, and
Thole
,
K. A.
,
2013
, “
Time-Resolved Film-Cooling Flows at High and Low Density Ratios
,”
ASME J. Turbomach.
,
136
(
6
), p.
061003
.
19.
Levenberg
,
K.
,
1944
, “
A Method for the Solution of Certain Non-Linear Problems in Least Squares
,”
Q. Appl. Math.
,
2
, pp.
164
168
.
20.
Marquardt
,
D.
,
1963
, “
An Algorithm for Least-Squares Estimation of Nonlinear Parameters
,”
J. Soc. Ind. Appl. Math.
,
11
(
2
), pp.
431
441
.
21.
Rutledge
,
J. L.
, and
Polanka
,
M. D.
,
2015
, “
Waveforms of Time-Resolved Film Cooling Parameters on a Leading Edge Model
,”
J. Propul. Power
,
31
(
1
), pp.
253
264
.
22.
Rutledge
,
J. L.
,
King
,
P. I.
, and
Rivir
,
R.
,
2010
, “
Time Averaged Net Heat Flux Reduction for Unsteady Film Cooling
,”
ASME J. Eng. Gas Turbines Power
,
132
(
12
), p.
121901
.
23.
Rutledge
,
J. L.
,
King
,
P. I.
, and
Rivir
,
R. B.
,
2012
, “
Influence of Film Cooling Unsteadiness on Turbine Blade Leading Edge Heat Flux
,”
ASME J. Eng. Gas Turbines Power
,
134
(
7
), p.
071901
.
24.
Giedt
,
W. H.
,
1949
, “
Investigation of Variation of Point Unit Heat-Transfer Coefficient Around a Cylinder Normal to an Air Stream
,”
Trans. ASME
,
71
, pp.
375
381
.
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