In core gas turbines relatively cold air is purged through the hub gap between the stator and rotor in order to seal the disk space against flow ingestion from the main annulus. Although the sealing mass flow rate is commonly very small compared to the main annulus mass flow rate, it can have significant effects on the development of the passage endwall flows and on the overall loss generation. In this paper, the interaction between the annulus and rim sealing flows is investigated using numerical simulations of a generic high-pressure turbine. At first, the numerical approach is validated by comparing the results of calculations to measurement data at the design flow conditions. Following that, results from steady and unsteady calculations are used to describe in detail the aerodynamics in overlap-type rim seals and their effects on the blade passage flow. It is found that the flow interaction at the rim seal interface is strongly influenced by the velocity deficit of the rim sealing flow relative to the annulus flow as well as by the circumferentially nonuniform pressure field imposed by the rotor blades. At typical sealing flow conditions, the flow interaction at the rim seal interface is found to be naturally unsteady, with periodical vortex shedding into the rotor passage. The rim seal geometry, in particular close to the annulus interface, is found to have an effect on the frequency of the shedding process. Finally, it is shown that the rim seal flow interaction can be stabilized by increasing either the sealing mass flow rate or the sealing tangential velocity.
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September 2013
Research-Article
Unsteady Interaction Between Annulus and Turbine Rim Seal Flows
Howard Hodson,
Howard Hodson
Whittle Laboratory,
University of Cambridge
,Cambridge
, UK
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David Newman
David Newman
Rolls-Royce plc
,Derby
, UK
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Martin Chilla
e-mail: mc618@cam.ac.uk
Howard Hodson
Whittle Laboratory,
University of Cambridge
,Cambridge
, UK
David Newman
Rolls-Royce plc
,Derby
, UK
Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received September 18, 2012; final manuscript received October 19, 2012; published online June 28, 2013. Editor: David Wisler.
J. Turbomach. Sep 2013, 135(5): 051024 (10 pages)
Published Online: June 28, 2013
Article history
Received:
September 18, 2012
Revision Received:
October 19, 2012
Citation
Chilla, M., Hodson, H., and Newman, D. (June 28, 2013). "Unsteady Interaction Between Annulus and Turbine Rim Seal Flows." ASME. J. Turbomach. September 2013; 135(5): 051024. https://doi.org/10.1115/1.4023016
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