A numerical study has been performed to investigate the effect of casing motion on the tip leakage flow and heat transfer characteristics in unshrouded axial flow turbines. The relative motion between the blade tip and the casing was simulated by moving the casing in a direction from the suction side to the pressure side of the stationary blade. Base line flat tip geometry and squealer type geometries, namely, double squealer or cavity and suction side squealer, were considered at a clearance gap of . The computations were performed using a single blade with periodic boundary conditions imposed along the boundaries in the pitchwise direction. Turbulence was modeled using the shear stress transport model. The flow conditions correspond to an exit Reynolds number of . The results were compared to those obtained without the relative casing motion reported in Part I of this paper. In general, the effect of relative casing motion was to decrease the tip leakage mass flow and the average heat transfer to the tip due to the decrease in leakage flow velocity caused by a drop in driving pressure difference. Compared to the computations with stationary casing, in the case of all the three geometries considered, the average heat transfer to the suction surface of the blade was found to be larger in the case of the computations with relative casing motion. At a larger clearance gap of , in case of a flat tip, while the tip leakage mass flow decreased due to relative casing motion, only a smaller change in the average heat transfer to the tip and the suction surface of the blade was noticed.
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January 2009
Research Papers
Aerothermal Investigations of Tip Leakage Flow in Axial Flow Turbines—Part II: Effect of Relative Casing Motion
S. K. Krishnababu,
S. K. Krishnababu
Department of Engineering,
University of Cambridge
, Cambridge CB2 1TN, UK
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W. N. Dawes,
W. N. Dawes
Department of Engineering,
University of Cambridge
, Cambridge CB2 1TN, UK
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H. P. Hodson,
H. P. Hodson
Department of Engineering,
University of Cambridge
, Cambridge CB2 1TN, 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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J. Hannis,
J. Hannis
Siemens Industrial Turbomachinery Ltd.
, P.O. Box 1, Waterside South, Lincoln LN5 7FD, UK
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C. Whitney
C. Whitney
Alstom Power Technology Centre
, Cambridge Road, Whetstone, Leicester LE8 6LH, UK
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S. K. Krishnababu
Department of Engineering,
University of Cambridge
, Cambridge CB2 1TN, UK
W. N. Dawes
Department of Engineering,
University of Cambridge
, Cambridge CB2 1TN, UK
H. P. Hodson
Department of Engineering,
University of Cambridge
, Cambridge CB2 1TN, UK
G. D. Lock
Department of Mechanical Engineering,
University of Bath
, Bath BA2 7AY, UK
J. Hannis
Siemens Industrial Turbomachinery Ltd.
, P.O. Box 1, Waterside South, Lincoln LN5 7FD, UK
C. Whitney
Alstom Power Technology Centre
, Cambridge Road, Whetstone, Leicester LE8 6LH, UKJ. Turbomach. Jan 2009, 131(1): 011007 (10 pages)
Published Online: October 3, 2008
Article history
Received:
August 27, 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 I: Effect of Tip Geometry and Tip Clearance Gap
Citation
Krishnababu, S. K., Dawes, W. N., Hodson, H. P., Lock, G. D., Hannis, J., and Whitney, C. (October 3, 2008). "Aerothermal Investigations of Tip Leakage Flow in Axial Flow Turbines—Part II: Effect of Relative Casing Motion." ASME. J. Turbomach. January 2009; 131(1): 011007. https://doi.org/10.1115/1.2952378
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