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Condensation phenomena in a turbine blade passage

Published online by Cambridge University Press:  26 April 2006

S. A. Skillings
S. A. Skillings
Affiliation:
CERL, Kelvin Avenue, Leatherhead, Surrey KT22 7SE, UK
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Abstract

The mechanisms associated with the formation and growth of water droplets in the large low-pressure turbines used for electrical power generation are poorly understood and recent measurements have indicated that an unusually high loss is associated with the initial nucleation of these droplets. In order to gain an insight into the phenomena which arise in the turbine situation, some experiments were performed to investigate the behaviour of condensing steam flows in a blade passage. This study has revealed the fundamental significance of droplet nucleation in modifying the single-phase flow structure and results are presented which show the change in shock wave pattern when inlet superheat and outlet Mach number are varied. The trailing-edge shock wave structure appears considerably more robust towards variations of inlet superheat than purely one-dimensional considerations may suggest and the inadequacies of adopting a one-dimensional theory to analyse multi-dimensional condensing flows are demonstrated. Over a certain range of outlet Mach numbers an oscillating shock wave will establish in the throat region of the blade passage and this has been shown to interact strongly with droplet nucleation, resulting in a considerably increased mean droplet size. The possible implications of these results for turbine performance are also discussed.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 200 , March 1989 , pp. 409 - 424
Copyright
© 1989 Cambridge University Press

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