A significant challenge of utilizing coal-derived synthetic fuels for gas turbine engines is mitigating the adverse effects of fuel-born contaminant deposits on film cooled turbine surfaces. A new experimental technique has been developed that simulates the key physical, but not the chemical, aspects of coal ash deposition on film cooled turbine airfoil leading edges in order to better understand the interaction between film cooling and deposition and to produce improved film cooling designs. In this large-scale wind tunnel facility, the depositing contaminants were modeled with atomized molten wax droplets sized to match the Stokes numbers of coal ash particles in the engine conditions. The sticking mechanism of the molten contaminants to the turbine surfaces was modeled by ensuring the wax droplets remained somewhat molten when they arrived at the cooled model surface. The airfoil model and wax deposits had thermal conductivities such that they matched the Biot numbers of clean and fouled turbine airfoils at engine conditions. The behavior of the deposit growth was controlled by adjusting the mainstream, coolant, and wax solidification temperatures. Simulated deposits were created for a range of test durations, film cooling blowing ratios, and controlling temperatures. Inspection of the resulting deposits revealed aspects of the flow field that augment and suppress deposition. Deposit thickness was found to increase in time until an equilibrium thickness was attained. Blowing ratio and the difference between mainstream and wax solidification temperatures strongly affected characteristics of the deposits. Model surface temperatures greatly reduced under the deposits as they developed.

References

References
1.
Walsh
,
P. M.
,
Sayre
,
A. N.
,
Loehden
,
D. O.
,
Monroe
,
L. S.
,
Beér
,
J. M.
, and
Sarofim
,
A. F.
, 1990, “
Deposition of Bituminous Coal Ash on an Isolated Heat Exchanger Tube: Effects of Coal Properties on Deposit Growth
,”
Prog. Energy Combust. Sci.
,
16
, pp.
327
346
.
2.
Rosner
,
D. E.
, and
Nagarajan
,
R.
, 1987, “
Toward a Mechanistic Theory of Net Deposit Growth From Ash-Laden Flowing Combustion Gases: Self-Regulated Sticking of Impacting Particles and Deposit Erosion in the Presence of Vapor Deposited – or Submicron Mist – ‘Glue,’
” AIChE Symp. Ser., Pittsburgh, PA, pp. 289–296.
3.
Wenglarz
,
R. A.
, and
Fox
,
R. G.
, 1990, “
Physical Aspects of Deposition From Coal-Water Fuels Under Gas Turbine Conditions
,”
J. Eng. Gas Turbines Power
,
112
, pp.
9
14
.
4.
Bons
,
J. P.
,
Crosby
,
J.
,
Wammack
,
J. E.
,
Bentley
,
B. I.
, and
Fletcher
,
T. H.
, 2007, “
High Pressure Turbine Deposition in Land-Based Gas Turbines From Various Synfuels
,”
J. Eng. Gas Turbines Power
,
129
, pp.
135
143
.
5.
Ai
,
W.
,
Murray
,
N.
,
Fletcher
,
T. H.
,
Harding
,
S.
,
Lewis
,
S.
, and
Bons
,
J. P.
, 2008, “
Deposition Near Film Cooling Holes on a High Pressure Turbine Vane
,” ASME Paper No. GT2008-50901.
6.
Mouzon
,
B. D.
,
Terrel
,
E. J.
,
Albert
,
J. E.
, and
Bogard
,
D. G.
, 2005, “
Net Heat Flux Reduction and Overall Effectiveness for a Turbine Blade Leading Edge
,” ASME Paper No. GT2005-69002.
7.
Maikell
,
J.
,
Bogard
,
D.
,
Piggush
,
J.
, and
Kohli
,
A.
, 2009, “
Experimental Simulation of a Film Cooled Turbine Blade Leading Edge Including Thermal Barrier Coating Effects
,”
J. Turbomach.
,
133
(
1
), p.
011014
.
8.
Richards
,
G. H.
,
Slater
,
P. N.
, and
Harb
,
J. N.
, 1993, “
Simulation of Ash Deposit Growth in a Pulverized Coal-Fired Pilot Scale Reactor
,”
Energy Fuels
,
7
(
6
), pp.
774
781
.
9.
Hinds
,
W. C.
, 1999,
Aerosol Technology: Properties, Behavior, and Measurement of Airborne Particles
,
Wiley-Interscience
,
New York
.
10.
Bons
,
J. P.
,
Taylor
,
R. P.
,
McClain
,
S. T.
, and
Rivir
,
R. B.
, 2001, “
The Many Faces of Turbine Surface Roughness
,”
J. Turbomach.
,
123
, pp.
739
748
.
You do not currently have access to this content.