Contours of heat transfer coefficient and effectiveness have been measured on the tip of a generic cooled turbine blade, using the transient liquid crystal technique. The experiments were conducted at an exit Reynolds number of in a five-blade linear cascade with tip clearances of 1.6% and 2.8% chord and featuring engine-representative cooling geometries. These experiments were supported by oil-flow visualization and pressure measurements on the tip and casing and by flow visualization calculated using CFX, all of which provided insight into the fluid dynamics within the gap. The data were compared with measurements taken from the uncooled tip gap, where the fluid dynamics is dominated by flow separation at the pressure-side edge. Here, the highest levels of heat transfer are located where the flow reattaches on the tip surface downstream of the separation bubble. A quantitative assessment using the net heat flux reduction (NHFR) revealed a significant benefit of ejecting coolant inside this separation bubble. Engine-representative blowing rates of approximately 0.6–0.8 resulted in good film-cooling coverage and a reduction in heat flux to the tip when compared to both the flat tip profile and the squealer and cavity tip geometries discussed in Part 1 of this paper. Of the two novel coolant-hole configurations studied, injecting the coolant inside the separation bubble resulted in an improved NHFR when compared to injecting coolant at the location of reattachment.
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January 2009
Research Papers
Aerothermal Investigations of Tip Leakage Flow in Axial Flow Turbines—Part III: TIP Cooling
P. J. Newton,
P. J. Newton
Department of Mechanical Engineering,
University of Bath
, Bath BA2 7AY, UK
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G. D. Lock,
G. D. Lock
Department of Mechanical Engineering,
University of Bath
, Bath BA2 7AY, UK
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S. K. Krishnababu,
S. K. Krishnababu
Whittle Laboratory, Department of Engineering,
University of Cambridge
, Cambridge CB2 1PZ, UK
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H. P. Hodson,
H. P. Hodson
Whittle Laboratory, Department of Engineering,
University of Cambridge
, Cambridge CB2 1PZ, UK
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W. N. Dawes,
W. N. Dawes
Whittle Laboratory, Department of Engineering,
University of Cambridge
, Cambridge CB2 1PZ, UK
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J. Hannis,
J. Hannis
Siemens Industrial Turbomachinery Ltd.
, Lincoln LN5 7FD, UK
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C. Whitney
C. Whitney
Alstom Power Technology Centre
, Leicester LN5 7FD, UK
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P. J. Newton
Department of Mechanical Engineering,
University of Bath
, Bath BA2 7AY, UK
G. D. Lock
Department of Mechanical Engineering,
University of Bath
, Bath BA2 7AY, UK
S. K. Krishnababu
Whittle Laboratory, Department of Engineering,
University of Cambridge
, Cambridge CB2 1PZ, UK
H. P. Hodson
Whittle Laboratory, Department of Engineering,
University of Cambridge
, Cambridge CB2 1PZ, UK
W. N. Dawes
Whittle Laboratory, Department of Engineering,
University of Cambridge
, Cambridge CB2 1PZ, UK
J. Hannis
Siemens Industrial Turbomachinery Ltd.
, Lincoln LN5 7FD, UK
C. Whitney
Alstom Power Technology Centre
, Leicester LN5 7FD, UKJ. Turbomach. Jan 2009, 131(1): 011008 (12 pages)
Published Online: October 3, 2008
Article history
Received:
June 14, 2007
Revised:
July 5, 2007
Published:
October 3, 2008
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Citation
Newton, P. J., Lock, G. D., Krishnababu, S. K., Hodson, H. P., Dawes, W. N., Hannis, J., and Whitney, C. (October 3, 2008). "Aerothermal Investigations of Tip Leakage Flow in Axial Flow Turbines—Part III: TIP Cooling." ASME. J. Turbomach. January 2009; 131(1): 011008. https://doi.org/10.1115/1.2950060
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