0
Research Papers

On Kinematic Relaxation and Deposition of Water Droplets in the Last Stages of Low Pressure Steam Turbines

[+] Author and Article Information
J. Starzmann

e-mail: starzmann@itsm.uni-stuttgart.de

M. V. Casey

Institute of Thermal Turbomachinery and Machinery Laboratory,
Pfaffenwaldring 6,
Stuttgart D-70569, Germany

F. Sieverding

Siemens AG,
Energy Sector,
Rheinstrasse 100,
Mülheim(Ruhr) D-45478, Germany

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received July 6, 2013; final manuscript received July 26, 2013; published online December 27, 2013. Editor: Ronald Bunker.

J. Turbomach 136(7), 071001 (Dec 27, 2013) (10 pages) Paper No: TURBO-13-1137; doi: 10.1115/1.4025584 History: Received July 06, 2013; Revised July 26, 2013

In the first part of the paper steady two-phase flow predictions have been performed for the last stage of a model steam turbine to examine the influence of drag between condensed fog droplets and the continuous vapor phase. In general, droplets due to homogeneous condensation are small and thus kinematic relaxation provides only a minor contribution to the wetness losses. Different droplet size distributions have been investigated to estimate at which size interphase friction becomes more important. The second part of the paper deals with the deposition of fog droplets on stator blades. Results from several references are repeated to introduce the two main deposition mechanisms which are inertia and turbulent diffusion. Extensive postprocessing routines have been programmed to calculate droplet deposition due to these effects for a last stage stator blade in three-dimensions. In principle the method to determine droplet deposition by turbulent diffusion equates to an approach for turbulent pipe flows and the advantages and disadvantages of this relatively simple method are discussed. The investigation includes the influence of different droplet sizes on droplet deposition rates and shows that for small fog droplets turbulent diffusion is the main deposition mechanism. If the droplets size is increased inertial effects become more and more important and for droplets around 1 μm inertial deposition dominates. Assuming realistic droplet sizes the overall deposition equates to about 1% to 3% of the incoming wetness for the investigated guide vane at normal operating conditions.

FIGURES IN THIS ARTICLE
<>
Copyright © 2014 by ASME
Your Session has timed out. Please sign back in to continue.

References

Gerber, A. G., Sigg, R., Völker, L., Casey, M. V., and Sürken, N., 2007, “Predictions of Nonequilibrium Phase Transition in a Model Low-Pressure Steam Turbine,” Proc. IMechE, J. Power Energy, 221(6), pp. 825–835. [CrossRef]
Wroblewski, W., Dykas, S., Gardzilewicz, A., and Kolovratnik, M., 2009, “Numerical and Experimental Investigation of Steam Condensation in LP Part of a Large Power Turbine,” ASME J. Fluids Eng., 131(4), p. 041301. [CrossRef]
Chandler, K., White, A., and Young, J. B., 2012, “Comparison of Unsteady Non-Equilibrium Wet-Steam Calculations With Model Turbine Data,” Baumann Centenary Wet Steam Conference, Cambridge, UK, September 10–11, Paper No. BCC-2012-10.
Starzmann, J., Casey, M., Mayer, J. F., and Sieverding, F., 2012, “Wetness Loss Prediction for a Low Pressure Steam Turbine Using CFD,” Baumann Centenary Wet Steam Conference, Cambridge, UK, September 10–11, Paper No. BCC-2012-14.
Young, J. B., 1982, “The Spontaneous Condensation of Steam in Supersonic Nozzles,” PhysicoChem. Hydrodyn., 3(1), pp. 57–82.
Starzmann, J., Schatz, M., Casey, M. V., Mayer, J. F., and Sieverding, F., 2011, “Modelling and Validation of Wet Steam Flow in a Low Pressure Steam Turbine,” ASME Paper No. GT2011-45672. [CrossRef]
Gerber, A. G., 2008, “Inhomogeneous Multifluid Model for Prediction of Nonequilibrium Phase Transition and Droplet Dynamics,” ASME J. Fluids Eng., 130(3), p. 031402. [CrossRef]
Schiller, L., and Nauman, A., 1933, “Über die Grundlegenden Berechnungen bei der Schwerkraftaufbereitung,” VDI Z. (1857–1968), 77, pp. 318–320.
Schatz, M., and Eberle, T., 2012, “Experimental Study of Steam Wetness in a Model Steam Turbine Rig: Presentation of Results and Comparison With CFD Data,” Baumann Centenary Wet Steam Conference, Cambridge, UK, September 10–11, Paper No. BCC-2012-09.
Gyarmathy, G., 1962, “Grundlagen einer Theorie der Nassdampfturbine,” Ph.D. thesis, ETH Zürich, Juris Verlag Zürich.
Young, J. B., and Yau, K. K., 1988, “The Inertial Deposition of Fog Droplets on Steam Turbine Blades,” ASME J. Turbomach., 110, pp. 155–162. [CrossRef]
Young, J., and Leeming, A., 1997, “A Theory of Particle Deposition in Turbulent Pipe Flow,” J. Fluid Mech., 340, pp. 129–159. [CrossRef]
Guha, A., 2008, “Transport and Deposition of Particles in Turbulent and Laminar Flow,” Ann. Rev. Fluid Mech., 40, pp. 311–341. [CrossRef]
Crane, R. I., 2004, “Droplet Deposition in Steam Turbines,” IMechE, 218, pp. 859–870. [CrossRef]
Reeks, M. W., 1983, “The Transport of Discrete Particles in Inhomogeneous Turbulence,” J. Aerosol Sci., 14(6), pp. 729–739. [CrossRef]
Guha, A., 1997, “A Unified Eulerian Theory of Turbulent Deposition to Smooth and Rough Surface,” J. Aerosol Sci., 28(8), pp. 1517–1537. [CrossRef]
Crane, R. I., 1973, “Deposition of Fog Drops on Low Pressure Steam Turbine Blades,” J. Mech. Sci., 15(8), pp. 613–631. [CrossRef]
Yau, K. K., and Young, J. B., 1987, “The Deposition of Fog Droplets on Steam Turbine Blades by Turbulent Diffusion,” ASME J. Turbomach., 109, pp. 429–435. [CrossRef]
Wood, N. B., 1981, “A Simple Method for the Calculation of Turbulent Deposition to Smooth and Rough Surfaces,” J. Aerosol Sci., 12, pp. 275–290. [CrossRef]
Young, J. B., Yau, K. K., and Walters, P. T., 1988, “Fog Droplet Deposition and Coarse Water Formation in Low-Pressure Steam Turbines: A Combined Experimental and Theoretical Analysis,” ASME, J. Turbomach., 110, pp. 163–172. [CrossRef]
Liu, B.Y.H., and Agarwal, J. K., 1974, “Experimental Observation of Aerosol Deposition in Turbulent Flow,” J. Aerosol Sci., 5, pp. 145–155. [CrossRef]
Johansen, S. T., 1991, “The Deposition of Particles on Vertical Walls,” Int. J. Multiphase Flow, 17(3), pp. 355–376. [CrossRef]
Reeks, M. W., 2005, “On Model Equations for Particle Dispersion in Inhomogeneous Turbulence,” Int. J. Multiphase Flow, 31, pp. 93–114. [CrossRef]
Slater, S. A., Leeming, A. D., and Young, J. B., 2003, “Particle Deposition From Two-Dimensional Turbulent Gas Flows,” Int. J. Multiphase Flow, 29, pp. 721–750. [CrossRef]
Shin, M., Kim, D. S., and Lee, J. W., 2003, “Deposition of Inertia-Dominated Particles Inside a Turbulent Boundary Layer,” Int. J. Multiphase Flow, 29, pp. 893–926. [CrossRef]
Reeks, M. W., and Skyrme, G., 1976, “The Dependence of Particle Deposition Velocity on Particle Inertia in Turbulent Pipe Flow,” J. Aerosol Sci., 7, pp. 485–495. [CrossRef]
Sigg, R., 2010, “Numerische Untersuchung von Lastvariationen und Nässephänomenen an einer Niederdruck-Dampfturbine,” Doctoral thesis, ITSM Universität Stuttgart, Shaker Verlag.

Figures

Grahic Jump Location
Fig. 1

Nucleation zones at design load conditions

Grahic Jump Location
Fig. 2

Mean droplet size predicted by homogeneous nucleation (D×1), measured and studied droplet sizes in E30

Grahic Jump Location
Fig. 3

Kinematic relaxation times of droplets

Grahic Jump Location
Fig. 4

Streamlines of the vapor phase in black and the liquid phase in blue with arrows

Grahic Jump Location
Fig. 5

Shadow regions shown by wetness contours in stator S3 at 50% span

Grahic Jump Location
Fig. 6

Secondary nucleation in stator S3 at 50% span

Grahic Jump Location
Fig. 7

Wetness fractions for D×4, upstream of stator S3 (E30), between stator S3 and rotor R3 (E31) and downstream of R3 (E32)

Grahic Jump Location
Fig. 8

Wetness fractions for D×8 case, upstream of stator S3 (E30), between stator S3 and rotor R3 (E31) and downstream of R3 (E32)

Grahic Jump Location
Fig. 9

Deposition regimes for turbulent pipe flows, taken from Young and Leeming [12]

Grahic Jump Location
Fig. 10

Evaluation of inertial deposition on the blade surface

Grahic Jump Location
Fig. 11

Relative deposition over span and profile length for different stator inlet droplet diameters

Grahic Jump Location
Fig. 12

Fractional deposition rates with respect to the inlet liquid mass flow at last stage stator

Grahic Jump Location
Fig. 13

Fractional deposition rates calculated for different streamtubes in the main flow region

Grahic Jump Location
Fig. 14

Comparison of inertial fractional deposition rates

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