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The influence of wake chopping on wet-steam turbine modelling

Accepted version
Peer-reviewed

Type

Conference Object

Change log

Authors

Schuster, S 

Abstract

jats:titleAbstract</jats:title> jats:pThe formation of water droplets within condensing steam turbines is a complex process that occurs at supersaturated, non-equilibrium conditions and is influenced by the unsteady segmentation of blade wakes by successive blade rows. This is often referred to as ‘wake chopping’, and its effect on the condensation process is the subject of this paper. The practical significance is that thermodynamic ‘wetness losses’ (which constitute a major fraction of the overall loss) are strongly affected by droplet size. Likewise, droplet deposition and the various ensuing two-phase phenomena (such as film migration and coarse-water formation) also depend on the spectrum of droplet sizes in the primary fog.</jats:p> jats:pThe majority of wake-chopping models presented in the literature adopt a stochastic approach, whereby large numbers of fluid particles are tracked through (some representation of) the turbine flowfield, assigning a random number at each successive blade row to represent the particle’s pitchwise location, and hence its level of dissipation. This study contributes to the existing literature by adding: (a) a comprehensive study of the sensitivity to key model parameters (e.g., blade wake shape and wake decay rate); (b) an assessment of the impact of circumferential pressure variations; (c) a study of the implications for wetness losses and (d) a study of the implications for deposition rates.</jats:p>

Description

Keywords

Wet steam, Condensation, Wake chopping, Wetness loss, Droplet deposition

Journal Title

Proceedings of the ASME Turbo Expo

Conference Name

ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition

Journal ISSN

Volume Title

9

Publisher

American Society of Mechanical Engineers

Rights

All rights reserved
Sponsorship
Engineering and Physical Sciences Research Council (EP/P004709/1)
General Electric