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Research Papers

Blade Tip Heat Transfer and Aerodynamics in a Large Scale Turbine Cascade With Moving Endwall

[+] Author and Article Information
P. Palafox

 GE Global Research Center, Niskayuna, NY 12301palafoxp@ge.com

M. L. G. Oldfield

Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, UKmartin.oldfield@eng.ox.ac.uk

P. T. Ireland

Turbines SCU, Rolls-Royce plc, Moor Lane, P.O. Box 32, Derby DE24 8BJ, UKpeter.ireland@rolls-royce.com

T. V. Jones

Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, UKterry.jones@eng.ox.ac.uk

J. E. LaGraff

Department of Mechanical and Aerospace Engineering, Syracuse University, Syracuse, NY 13244jlagraff@syr.edu

J. Turbomach 134(2), 021020 (Jun 30, 2011) (11 pages) doi:10.1115/1.4003085 History: Received August 03, 2010; Revised August 12, 2010; Published June 30, 2011; Online June 30, 2011

High resolution Nusselt number distributions were measured on the blade tip surface of a large, 1.0 m chord, low-speed cascade representative of a high-pressure turbine. Data were obtained at a Reynolds number of 4.0×105 based on exit velocity and blade axial chord. Tip clearance levels ranged from 0.56% to 1.68% design span or equally from 1% to 3% of the blade chord. An infrared camera, looking through the hollow blade, made detailed temperature measurements on a constant heat flux tip surface. The relative motion between the endwall and the blade tip was simulated by a moving belt. The moving belt endwall significantly shifts the region of high Nusselt number distribution and reduces the overall averaged Nusselt number on the tip surface by up to 13.3%. The addition of a suction side squealer tip significantly reduced local tip heat transfer and resulted in a 32% reduction in averaged Nusselt number. Analysis of pressure measurements on the blade airfoil surface and tip surface along with particle image velocimetry velocity flow fields in the gap gives an understanding of the heat transfer mechanism.

Copyright © 2012 by American Society of Mechanical Engineers
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References

Figures

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Figure 1

Cascade geometry and test conditions. The cascade was mounted in an existing large wind tunnel.

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Figure 2

Cascade test section and moving belt

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Figure 3

Location of measurement planes perpendicular to tip surface inside gap

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Figure 4

Heat transfer experiment set up

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Figure 5

Copper heater strips serpentine design

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Figure 6

Layers of material comprising blade tip

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Figure 7

PIV flow field for t/b=1.68% with no relative motion (previously presented in Ref. 10)

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Figure 8

PIV flow field for t/b=1.68% with relative motion (previously presented in Ref. 10)

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Figure 9

Perpendicular leakage flow at 63.5 cm from TE for t/b=1.68% (previously presented in Ref. 10)

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Figure 10

Perpendicular leakage flow at 43.5 cm from TE for t/b=1.68%

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Figure 11

Perpendicular leakage flow at 23.5 cm from TE for t/b=1.68%

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Figure 12

CP distribution for flat tip with t/b=1.68%

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Figure 13

CP distribution for flat tip with t/b=0.84%

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Figure 14

CP distribution for flat tip with t/b=0.56%

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Figure 15

CP distribution for suction side squealer tip with t/b=0.84%

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Figure 16

Airfoil pressure distributions at 10%C from tip

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Figure 17

Nu map for flat tip with t/b=1.68%

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Figure 18

Nu map for flat tip with t/b=0.84%

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Figure 19

Nu map for flat tip with t/b=0.56%

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Figure 20

Nu map for suction side squealer with t/b=0.84%

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