A numerical study has been performed to investigate the effect of tip geometry on the tip leakage flow and heat transfer characteristics in unshrouded axial flow turbines. Base line flat tip geometry and squealer type geometries, namely, double squealer or cavity and suction-side squealer, were considered. The performances of the squealer geometries, in terms of the leakage mass flow and heat transfer to the tip, were compared with the flat tip at two different tip clearance gaps. The computations were performed using a single blade with periodic boundary conditions imposed along the boundaries in the pitchwise direction. Turbulence was modeled using three different models, namely, standard , low Re , and shear stress transport (SST) , in order to assess the capability of the models in correctly predicting the blade heat transfer. The heat transfer and static pressure distributions obtained using the SST model were found to be in close agreement with the experimental data. It was observed that compared to the other two geometries considered, the cavity tip is advantageous both from the aerodynamic and from the heat transfer perspectives by providing a decrease in the amount of leakage, and hence losses, and average heat transfer to the tip. In general, for a given geometry, the leakage mass flow and the heat transfer to the tip increased with increase in tip clearance gap. Part II of this paper examines the effect of relative casing motion on the flow and heat transfer characteristics of tip leakage flow. In Part III of this paper the effect of coolant injection on the flow and heat transfer characteristics of tip leakage flow is presented.
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January 2009
Research Papers
Aerothermal Investigations of Tip Leakage Flow in Axial Flow Turbines—Part I: Effect of Tip Geometry and Tip Clearance Gap
S. K. Krishnababu,
S. K. Krishnababu
Department of Engineering,
University of Cambridge
Cambridge CB2 1PZ, UK
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P. J. Newton,
P. J. Newton
Department of Mechanical Engineering,
University of Bath
Bath BA2 7AY, UK
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W. N. Dawes,
W. N. Dawes
Department of Engineering,
University of Cambridge
Cambridge CB2 1PZ, 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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H. P. Hodson,
H. P. Hodson
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
, LN5 7SD, UK
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S. K. Krishnababu
Department of Engineering,
University of Cambridge
Cambridge CB2 1PZ, UK
P. J. Newton
Department of Mechanical Engineering,
University of Bath
Bath BA2 7AY, UK
W. N. Dawes
Department of Engineering,
University of Cambridge
Cambridge CB2 1PZ, UK
G. D. Lock
Department of Mechanical Engineering,
University of Bath
Bath BA2 7AY, UK
H. P. Hodson
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
, LN5 7SD, UKJ. Turbomach. Jan 2009, 131(1): 011006 (14 pages)
Published Online: October 3, 2008
Article history
Received:
June 30, 2007
Revised:
January 4, 2008
Published:
October 3, 2008
Connected Content
A companion article has been published:
Aerothermal Investigations of Tip Leakage Flow in Axial Flow Turbines—Part II: Effect of Relative Casing Motion
A companion article has been published:
Aerothermal Investigations of Tip Leakage Flow in Axial Flow Turbines—Part III: TIP Cooling
Citation
Krishnababu, S. K., Newton, P. J., Dawes, W. N., Lock, G. D., Hodson, H. P., Hannis, J., and Whitney, C. (October 3, 2008). "Aerothermal Investigations of Tip Leakage Flow in Axial Flow Turbines—Part I: Effect of Tip Geometry and Tip Clearance Gap." ASME. J. Turbomach. January 2009; 131(1): 011006. https://doi.org/10.1115/1.2950068
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