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Research Papers

Adiabatic and Overall Effectiveness for the Showerhead Film Cooling of a Turbine Vane

[+] Author and Article Information
Marc L. Nathan

e-mail: Marc.Nathan@utexas.edu

Thomas E. Dyson

e-mail: tedyson@gmail.com

David G. Bogard

e-mail: dbogard@mail.utexas.edu
The University of Texas at Austin,
Austin, TX 78712

Sean D. Bradshaw

Pratt & Whitney,
East Hartford, CT 06108
e-mail: sean.bradshaw@pw.utc.com

1Currently at Cameron International, Houston, TX 77027.

2Currently at GE Global Research, Niskayuna, NY 12309.

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received February 15, 2013; final manuscript received March 17, 2013; published online September 26, 2013. Editor: David Wisler.

J. Turbomach 136(3), 031005 (Sep 26, 2013) (9 pages) Paper No: TURBO-13-1023; doi: 10.1115/1.4024680 History: Received February 15, 2013; Revised March 17, 2013

There have been a number of previous studies of the adiabatic film effectiveness for the showerhead region of a turbine vane, but no previous studies of the overall cooling effectiveness. The overall cooling effectiveness is a measure of the external surface temperature relative to the mainstream temperature and the inlet coolant temperature, and consequently is a direct measure of how effectively the surface is cooled. This can be determined experimentally when the model is constructed so that the Biot number is similar to that of engine components, and the internal cooling is designed so that the ratio of the external to internal heat transfer coefficient is matched to that of the engine. In this study, the overall effectiveness was experimentally measured on a model turbine vane constructed of a material to match Bi for engine conditions. The model incorporated an internal impingement cooling configuration. The cooling design consisted of a showerhead composed of five rows of holes with one additional row on both pressure and suction sides of the vane. An identical model was also constructed out of low conductivity foam to measure adiabatic film effectiveness. Of particular interest in this study was to use the overall cooling effectiveness measurements to identify local hot spots which might lead to failure of the vane. Furthermore, the experimental measurements provided an important database for evaluation of computational fluid dynamics simulations of the conjugate heat transfer effects that occur in the showerhead region. Continuous improvement in both measures of performance was demonstrated with increasing momentum flux ratio.

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References

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Figures

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Fig. 1

TTCRL wind tunnel test section schematic

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Fig. 2

Measured pressure distribution compared to the predicted infinite cascade of Dees et al. [12]

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Fig. 3

Test vane schematic with close-up of showerhead region

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Fig. 4

Coolant flow-path diagram

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Fig. 10

Contours of (a) η, ISH* = 2.92 and (b) ϕ, ISH* = 2.99 with highlighted zones of corresponding low performance

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Fig. 9

Contours of η for (a) ISH* = 0.76 (b) ISH* = 1.72 and (c) ISH* = 2.99 (d) ISH* = 4.64 and (e) ISH* = 6.70

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Fig. 8

η¯ for all measured momentum flux ratio

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Fig. 7

Detailed view of η contours for (a) ISH* = 0.76 (b) ISH* = 2.92 and (c) ISH* = 6.73 pointing out important features

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Fig. 6

Contours of η for (a) ISH* = 0.76 (b) ISH* = 1.74 and (c) ISH* = 2.92 (d) ISH* = 4.67 and (e) ISH* = 6.73

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Fig. 5

Schematic view depicting the viewing areas for the cameras

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Fig. 11

φ¯ for all measured momentum flux ratios

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Fig. 12

Comparison of η¯ and φ¯ at ISH* = 0.8, 3.0 and 6.7

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Fig. 13

Measured values of h0 for a smooth C3X vane from Dees et al. [12]

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