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Impingement Cooling with Spent Flow in the Blade Leading Edge Using Double Swirl Chambers

DOI: 10.1615/IHTC15.hte.008669
pages 4291-4305

Gang Lin
B&B-AGEMA GmbH

Karsten Kusterer
B&B-AGEMA, Gesellschaft für Energietechnische Maschinen und Anlagen, Aachen

Dieter Bohn
Institute of Steam and Gas Turbines, Aachen University of Technology, Aachen

Takao Sugimoto
Kawasaki Heavy Industries, LTD., Gas Turbine & Machinery Company

Ryozo Tanaka
Kawasaki Heavy Industries, LTD., Gas Turbine & Machinery Company

Masahide Kazari
Kawasaki Heavy Industries, LTD., Technical Institute


KEY WORDS: Heat transfer enhancement, Gas turbine, impingement, spent flow, leading edge, double swirl chambers

Abstract

Leading edge of a turbine blade has the most critical heat-transfer area. The highest heat-transfer rates on the airfoil can always be found on the stagnation region of the leading edge. In order to further improve the turbine thermal efficiency the development of more advanced internal cooling configurations at leading edge is very necessary. As the state of the art leading edge cooling configuration a concave channel with multi inline jets has been widely used in the most blades. This kind of configuration can generate strong spent flow, which shifts the impingement from the stagnation point and weaken the impingement heat transfer. In order to solve this problem a new internal cooling configuration using double swirl chambers in turbine leading edge has been developed and introduced in this paper. The double swirl chambers cooling (DSC) technology is introduced by the authors and comprises a significant enhancement of heat transfer due to the generation of two anti-rotated swirls. In DSC-cooling, the reattachment of the swirl flows always occurs at the middle of the chamber, which results in a linear impingement effect. Within the numerical study for DSC leading edge cooling configuration with multi inline jets, the spent flow cannot shift the position of the impingement line and cannot weaken the impingement heat transfer especially at the second half chamber. Compared with the reference standard impingement cooling configuration this new cooling system provides a much more uniform heat transfer distribution in the chamber axial direction and also provides much higher heat transfer rate. With the same inlet slots and the same Reynolds number based on hydraulic diameter of inlet slot this new cooling configuration shows much better globally averaged thermal performance factor.

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