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On- and off-design performance of a model rotating turbine with non-axisymmetric endwall contouring and a comparison to cascade data

Part of: ISABE 2017

Published online by Cambridge University Press:  21 March 2018

G. Snedden ,
D. Dunn  and
G. Ingram
G. Snedden*
Affiliation:
CSIR DPSS, Pretoria, South Africa
D. Dunn
Affiliation:
CSIR DPSS, Pretoria, South Africa
G. Ingram
Affiliation:
Department of Engineering, Durham University, Durham, UK
*
gsnedden@csir.co.za
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Abstract

Non-axisymmetric endwalls in turbine stages have shown to be a robust method to improve the performance of turbines in both power generation and aero-derivative applications. Non-axisymmetric endwalls target the control of secondary flows and are designed using detailed computational fluid dynamics coupled with a variety of optimisation algorithms and utilising a number of objective functions according to the engine company or researcher's preference. These numerical predictions are often backed up by detailed measurements in linear and annular cascades and later proven in full-scale engine tests. Relatively little literature is available describing their performance in rotating test rigs or at conditions other than design, apart from that of the authors. This study comprehensively revisits the low-speed, model turbines used in the earlier study, replacing all of the 5-hole probe data with more accurate results and additional hot-film measurements. These results together with computational fluid dynamics solutions are used to show the success of the method across a large incidence range and to compare to earlier cascade results for a similar endwall and blade profile to establish the usefulness of cascade testing in this application. In addition, a comparison to two other off-design studies is made. Results indicate that the endwalls successfully improve the rotor total isentropic efficiency at all test conditions and that the improvement increases with increased turning in the blade row, from 0.5% to 1.8% across the incidence range. The results also compare well to the estimation of isentropic efficiency improvement that can be drawn from the cascade testing which stands at 1.55%.

Keywords

Non-axisymmetric endwall contouringturbine efficiencysecondary flows
Type
Research Article
Information
The Aeronautical Journal , Volume 122 , Issue 1250 , April 2018 , pp. 646 - 665
Copyright
Copyright © Royal Aeronautical Society 2018 

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Footnotes

A version of this paper was presented at the ISABE 2017 Conference, 3-8 September 2017, Manchester, UK

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