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Research Papers

Aerothermal Performance of a Cooled Winglet at Engine Representative Mach and Reynolds Numbers

[+] Author and Article Information
D. O. O’Dowd, L. He

Department of Engineering Science,
Parks Road, University of Oxford,
Oxford, OX1 3PJ, United Kingdom

Q. Zhang

University of Michigan-Shanghai Jiao Tong
University Joint Institute,
Shanghai Jiao Tong University,
Shanghai, China
e-mail: qzhang@sjtu.edu.cn

I. Tibbott

Rolls-Royce plc,
Turbine Systems,
Derby, United Kingdom

Contributed by the International Gas Turbine Institute (IGTI)) of ASME for publication in the Journalof Turbomachinery. Manuscript received August 14, 2011; final manuscript received August 31, 2011; published online October 31, 2012. Editor: David Wisler.

J. Turbomach 135(1), 011041 (Oct 31, 2012) (10 pages) Paper No: TURBO-11-1183; doi: 10.1115/1.4006537 History: Received August 14, 2011; Revised August 31, 2011

This paper presents an experimental investigation of the aerothermal performance of a cooled winglet tip under transonic conditions (exit Mach number of 1.0, and an exit Reynolds number of 1.27 × 106, based on axial chord). Spatially resolved heat transfer data and film cooling effectiveness data are obtained using the transient infrared thermography technique in the Oxford High-Speed Linear Cascade test facility. Aerodynamic loss data are obtained by traversing a specially made and calibrated three-hole pressure probe and a single-hole probe one axial chord downstream of the blade. Detailed contours of Nusselt number show that for an increase in tip clearance, with and without film cooling, and for coolant injection, for both tip clearances, the Nusselt number increases. Also the smaller tip clearance observes higher film cooling effectiveness overall. Detailed distributions of kinetic energy losses as well as pitch-wise averaged loss coefficients and loss coefficients at a mixed-out plane indicate that the size of the loss core associated with the over-tip leakage vortex decreases with cooling injection.

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Figures

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Fig. 1

The schematic of the oxford high speed linear cascade research facility

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Fig. 2

The schematics of the test section and instrumentation

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Fig. 3

The schematics of the winglet tips tested in the HSLC (slightly modified from [44,45-44,45]) for the (a) uncooled winglet and (b) cooled winglet

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Fig. 4

Schematic of test plenum, including coolant supply, settling chamber, solenoid switch, and bypass feed

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Fig. 5

Experimental Nusselt number for 1.5% tip clearance for the uncooled and cooled winglets

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Fig. 6

Experimental Nusselt number for 1.0% tip clearance for the uncooled and cooled winglets

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Fig. 7

Experimental circumferentially averaged Nusselt number both uncooled and cooled winglet for 1.0% and 1.5% tip clearances

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Fig. 8

Experimental film cooling effectiveness for both 1.5% and 1.0% tip gaps

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Fig. 9

Experimental circumferentially averaged film cooling effectiveness for 1.0% and 1.5% tip clearances

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Fig. 10

Predicted Mach number for both 1.5% and 1.0% tip gaps

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Fig. 11

Experimental loss coefficient ζ for 1.5%

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Fig. 12

Experimental loss coefficient ζ for 1.0%

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Fig. 13

Pitch-wise mass-averaged loss coefficients ζ for 1.5% and 1.0% tip gaps

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Fig. 14

Loss coefficient ζ for mixed-out plane

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