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Research Papers

Coal Ash Deposition on Nozzle Guide Vanes—Part II: Computational Modeling

[+] Author and Article Information
J. P. Bons

Department of Mechanical
and Aerospace Engineering
Ohio State University
Columbus, OH, 43235

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received July 15, 2011; final manuscript received August 16, 2011; published online November 6, 2012. Editor: David Wisler.

J. Turbomach 135(1), 011015 (Nov 06, 2012) (9 pages) Paper No: TURBO-11-1139; doi: 10.1115/1.4006399 History: Received July 15, 2011; Revised August 16, 2011

Coal ash deposition was numerically modeled on a GE-E3 high pressure turbine vane passage. A model was developed, in conjunction with FLUENT™ software, to track individual particles through the turbine passage. Two sticking models were used to predict the rates of deposition which were subsequently compared to experimental trends. The strengths and limitations of the two sticking models, the critical viscosity model and the critical velocity model, are discussed. The former model ties deposition exclusively to particle temperature while the latter considers both the particle temperature and velocity. Both incorporate some level of empiricism, though the critical viscosity model has the potential to be more readily adaptable to different ash compositions. Experimental results show that both numerical models are reasonably accurate in predicting the initial stages of deposition. Beyond the initial stage of deposition, for which transient effects must be accounted.

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Figures

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Fig. 1

GE-E3 turbine vane grid used in FLUENT flow solver

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Fig. 2

Representation of injection point grid where ash particles were initially tracked

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Fig. 5

Midspan view of path lines of three injected particles. Red = 100 μm diameter, green = 10 μm diameter, and blue = 1 μm diameter. No sticking model is incorporated.

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Fig. 4

Particle size distribution results from Coulter Counter for JBPS coal fly ash

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Fig. 3

Midspan view of fluid streamlines around vane surface (a) and contours of local Mach (b)

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Fig. 6

Relationship between Stokes number and impact efficiency (only single impacts are allowed–no rebound)

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Fig. 7

Impact efficiency versus Stokes number (particle diameter) for critical viscosity and critical velocity models (multiple impacts are allowed)

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Fig. 8

Sticking efficiency versus Stokes number (particle diameter) for critical viscosity and critical velocity models

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Fig. 9

Capture efficiency versus Stokes number (particle diameter) for critical viscosity and critical velocity models

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Fig. 10

Deposition concentration using critical viscosity model

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Fig. 11

Deposition concentration using critical velocity model

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Fig. 12

JBPS fly ash ∼1050 °C post test

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Fig. 13

Right image shows initial formation of ash deposition in experimental test. Left image shows clean vanes for spatial reference.

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Fig. 14

Lignite fly ash ∼1050 °C post test

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