0
Research Papers

Effect of Blowing Ratio on Early Stage Deposition of Syngas Ash on a Film-Cooled Vane Leading Edge Using Large Eddy Simulations

[+] Author and Article Information
Danesh K. Tafti

e-mail: dtafti@vt.eduHigh Performance Computational Fluid-Thermal
Sciences and Engineering Laboratory,
Mechanical Engineering Department,
Virginia Polytechnic Institute and
State University,
Blacksburg VA 24061

The notation (aj)i is used to denote the ith component of vector aj, (aj)i=ξj/xi.

For an estimate of the lowest radiative Stokes number (Tp=T).

The values of A are corrected values pointed out by Vargas [26].

The computations assume a coolant to mainstream density ratio of 1 (see Table 3).

1Presently at: ATMS, GE Global Research, 122, EPIP, Whitefield Road, Bangalore 560 066, Karnataka, India.

2Corresponding author.

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received October 29, 2010; final manuscript received August 5, 2011; published online September 13, 2013. Assoc. Editor: Karen A. Thole.

J. Turbomach 135(6), 061005 (Sep 13, 2013) (12 pages) Paper No: TURBO-10-1205; doi: 10.1115/1.4025153 History: Received October 29, 2010; Revised August 05, 2011

A numerical study is performed to investigate the deposition of Syngas ash in the leading edge region of a turbine vane. The leading edge of the vane is modeled as a symmetric semicylinder with a flat afterbody. Three rows of coolant holes located at stagnation and at ±21.3 deg from stagnation are simulated at blowing ratios of 0.5, 1.0, 1.5, and 2.0. Large eddy simulation (LES) is used to model the flow field of the coolant jet-mainstream interaction and Syngas ash particles are modeled using a discrete particle method. The capture efficiency for eight different ash compositions of particle sizes 5 and 10 microns are investigated. Under the conditions of the current simulations, both ash particles have Stokes numbers less than unity and hence are strongly affected by the flow and thermal field generated by the coolant interaction with the mainstream. Because of this, the coolant jets at stagnation are quite successful in pushing the particles away from the surface and minimizing deposition in the stagnation region. Among all of the ash samples, the ND ash sample shows the highest capture efficiency due to its low softening temperature. For the 5 micron particles, when the blowing ratio increases from 1.5 to 2.0, the percentage of the capture efficiency increases as more numbers of particles are transported to the surface by strong mainstream entrainment by the coolant jets. The deposition results are also estimated using the discrete random walk (DRW) model and are compared to that obtained from the LES calculations. For both particle sizes, the DRW model under-predicts the capture efficiency when compared to the LES calculations and the difference increases with the increasing blowing ratio and decreases with increasing particle size.

FIGURES IN THIS ARTICLE
<>
Copyright © 2013 by ASME
Your Session has timed out. Please sign back in to continue.

References

Wenglarz, R. D., 1985, “Deposition, Erosion and Corrosion Protection for Coal-Fired Gas Turbine,” ASME Paper No. 85-IGTI-61.
Tabakoff, W., 1991, “Measurements of Particles Rebound Characteristics on Materials Used in Gas Turbines,” J. Propul. Power, 7(5), pp. 805–813. [CrossRef]
Bons, J. P., Crosby, J., Wammack, J. E., Bentley, B. I., and Fletcher, T., 2005, “High Pressure Turbine Deposition in Land Based Gas Turbines From Various Synfuels,” ASME Paper No. GT2005-68479. [CrossRef]
Schmidt, D. L., Sen, B., and Bogard, D. G., 1996, “Effects of Surface Roughness on Film Cooling,” ASME Paper No. 95-GT-299.
Bunker, R., 2000, “Effect of Partial Coating Blockage on Film Cooling Effectiveness,” ASME Paper No. 2000-GT-244.
Bons, J. P., Taylor, R., McClain, S. T., and Rivir, R. B., 2001, “The Many Faces of Turbine Surface Roughness,” ASME J. Turbomach., 123, pp. 739–748. [CrossRef]
Menguturk, M., and Sverdrup, E. F., 1982, “A Theory for Fine Particle Deposition in Two-Dimensional Boundary Layer Flows and Application to Gas Turbines,” ASME J. Eng. Power, 104, pp. 69–76. [CrossRef]
Ahluwalia, R. K., Im, K. H., and Wenglarz, R. A., 1989, “Flyash Adhesion in Simulated Coal-Fired Gas Turbine Environment,” ASME J. Eng. Gas Turbines Power, 111, pp. 672–678. [CrossRef]
Stringer, J., and Drenker, S., 1981, “Turbine Erosion Problems and Hot Gas Clean-Up Requirements for PFB Combustion,” Proc. Am. Power Conf., 43, p. 943.
Wammack, J. E., Crosby, J., Fletcher, D., Bons, J. P., and Fletcher, T., 2006, “Evolution of Surface Deposits on a High Pressure Turbine Blade—Part I: Physical Characteristics,” ASME Paper No. GT2006-91246. [CrossRef]
Crosby, J. M., Lewis, S., Bons, J. P., Ai, W., and Fletcher, T., 2007, “Effects of Particle Size, Gas Temperature, and Metal Temperature on High Pressure Turbine Deposition in Land Based Gas Turbines From Various Synfuels,” ASME Paper No. GT2007-27531. [CrossRef]
Ai, W., Murray, N., Fletcher, T., 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. [CrossRef]
Hamed, A., Tabakoff, W., and Wenglarz, R., 2006, “Erosion and Deposition in Turbomachinery,” J. Propul. Power, 22(2), pp. 350–360. [CrossRef]
Shah, A., and Tafti, D., 2007, “Transport of Particulates in an Internal Cooling Ribbed Duct,” ASME J. Turbomach., 129(4), pp. 816–825. [CrossRef]
Rozati, A., Tafti, D., and Sreedharan, S., 2011, “Effect of Syngas Ash Particle Size on Deposition and Erosion of a Film Cooled Leading Edge,” ASME J. Turbomach., 133(1), p. 011010. [CrossRef]
Sreedharan, S. S., and Tafti, D., 2009, “Effect of Blowing Ratio on Syngas Flyash Particle Deposition on a Three-Row Leading Edge Film Cooling Geometry Using Large Eddy Simulations,” ASME Paper No. GT2009-59326. [CrossRef]
Sreedharan, S. S., and Tafti, D., 2010, “Composition Dependent Model for the Prediction of Syngas Ash Deposition in Turbine Gas Hotpath,” Int. J. Heat Fluid Flow (submitted).
Germano, M., Piomelli, U., Moin, P., and Cabot, W. H., 1991, “A Dynamic Subgrid-Scale Eddy Viscosity Model,” Phys. Fluids A, 3, pp. 1760–1765. [CrossRef]
Moin, P., Squires, K., and Cabot, W. H., 1991, “A Dynamic Subgrid Model for Compressible Turbulence and Scalar Transport,” Phys. Fluids A, 3, pp. 2746–2757. [CrossRef]
Shah, A., 2005, “Development and Application of a Dispersed Two-Phase Flow Capability in a General Multi-Block Navier–Stokes Solver,” Master's thesis, Virginia Tech, Blacksburg, VA.
Klienstreuer, C., 2003, Two Phase Flow: Theory and Applications, Taylor & Francis, London.
Graham, D. I., and James, P. W., 1995, “Turbulent Dispersion of Particles Using Eddy Interaction Models,” Int. J. Multiphase Flow, 22(1), pp. 157–175. [CrossRef]
Gosman, A. D., and Ioannides, E., 1983 “Aspects of Computer Simulation of Liquid-Fueled Combustors,” J. Energy, 7(6), pp. 482–490. [CrossRef]
Walsh, P. M., Sayre, A. N., Loehden, D. O., Monroe, L. S., Beer, 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. 327–334. [CrossRef]
Senior, S. L., and Srinivasachar, S., 1995, “Viscosity of Ash Particles in Combustion Systems for Prediction of Particle Sticking,” Energy Fuels, 9, pp. 277–283. [CrossRef]
Vargas, S., 2001, “Straw and Coal Ash Rheology,” PhD thesis, Dept. of Chemical Eng., Technical University of Denmark, Lyngby, Denmark, pp. 53–61.
Yin, C., Luo, Z., Ni, M., and Cen, K., 1998, “Predicting Coal Ash Fusion Temperature With a Back-Propagation Neural Network Model,” Fuel, 77(17), pp. 1777–1782. [CrossRef]
Ledesma, M., and Isaacs, L. L., 1990, “Thermal Properties of Coal Ash,” MRS Proceedings, 178, p. 35. [CrossRef]
Mbabazi, J. G., Sheer, T. J., and Shandu, R., 2004, “A Model to Predict Erosion on Mild Steel Surfaces Impacted by Boiler Fly Ash Particles,” Wear, 257, pp. 612–624. [CrossRef]
Li, H., Yoshihiko, N., Dong, Z., and Zhang, H., 2006, “Application of the Facts—Age to Predict the Ash Melting Behavior in Reducing Conditions,” Chin. J. Chem. Eng., 14(6), pp. 784–789. [CrossRef]
Tafti, D., 2001, “Genidlest—A Scalable Parallel Computational Tool for Simulating Complex Turbulent Flows,” Proceedings of the ASME Fluids Engineering Division, Vol. 256, pp. 347–356.

Figures

Grahic Jump Location
Fig. 1

Transition to the modified deposition model using the critical viscosity approach (Ps is the sticking probability and Ts is the ash softening temperature [15])

Grahic Jump Location
Fig. 2

Temperature-viscosity variation for various ash samples

Grahic Jump Location
Fig. 3

Leading edge vane model and near field streamwise planes used in presenting the results

Grahic Jump Location
Fig. 4

Computational domain in the side view (X-Y plane)

Grahic Jump Location
Fig. 5

Structure of coherent vorticity: (a) BR = 0.5 (iso-surface value = 30), and (b) BR = 2.0 (iso-surface value = 75)

Grahic Jump Location
Fig. 6

Effectiveness on the vane surface: (a) BR = 0.5, (b) BR = 1.0, (c) BR = 1.5, and (d) BR = 2.0

Grahic Jump Location
Fig. 7

Lateral span averaged effectiveness on the vane surface

Grahic Jump Location
Fig. 8

Impact efficiency as a function of the blowing ratio

Grahic Jump Location
Fig. 9

Capture efficiency as a function of the blowing ratio for the ND ash sample (see Table 2)

Grahic Jump Location
Fig. 10

Percentage capture efficiency of 5 μm ash particles on the leading edge vane surface for the ND ash sample (the direction of the coolant is from right to left)

Grahic Jump Location
Fig. 11

Percentage capture efficiency of 10 μm ash particles on the leading edge vane surface for the ND ash sample (the direction of the coolant is from right to left)

Grahic Jump Location
Fig. 12

Capture efficiency for all ash samples having a particle size of 5 μm at different blowing ratios (the dotted horizontal line indicates the deposition at Tsoft = 1500 K, independent of ash composition)

Grahic Jump Location
Fig. 13

Capture efficiency for all ash samples having a particle size of 10 μm at different blowing ratios (the dotted horizontal line indicates the deposition at Tsoft = 1500 K, independent of ash composition)

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In