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Research Papers

Convex Curvature Effects on Film Cooling Adiabatic Effectiveness

[+] Author and Article Information
James R. Winka

The University of Texas at Austin,
Austin, TX 78712
e-mail: jwinka@gmail.com

Joshua B. Anderson

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

Emily J. Boyd

The University of Texas at Austin,
Austin, TX 78712
e-mail: emily.june.boyd@gmail.com

David G. Bogard

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

Michael E. Crawford

Siemens Energy,
Orlando, FL 32826
e-mail: michaelcrawford@siemens.com

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received July 22, 2013; final manuscript received August 22, 2013; published online November 28, 2013. Editor: Ronald Bunker.

J. Turbomach 136(6), 061015 (Nov 28, 2013) (9 pages) Paper No: TURBO-13-1165; doi: 10.1115/1.4025691 History: Received July 22, 2013; Revised August 22, 2013

Surface curvature is known to have significant effects on film cooling performance, with convex curvature inducing increased film effectiveness and concave curvature causing decreased film effectiveness. Generally, these curvature effects have been presumed to scale with 2r/d at the film cooling hole location, where r is the radius of curvature and d is coolant hole diameter. In this study, the validity of this scaling of curvature effects are examined by performing experiments in regions of large and low curvature on a model vane. Single rows of cylindrical holes were placed at various locations along the high curvature section of the suction side of the vane. For the first series of experiments, a single row of holes was placed at two locations with different local surface curvature. The coolant hole diameters were then adjusted to match 2r/d values. Results from these experiments showed that there was better correspondence of film performance when using the 2r/d scaling, but there was not an exact matching of performance. A second series of experiments focused on evaluating the effects of curvature downstream of the coolant holes. One row of holes was placed at a position upstream of the highest curvature, while another row was placed at a downstream position such that the radius of curvature was equivalent for the two rows of holes. Results indicated that the local radius of curvature is not sufficient in understanding the performance of film cooling. Instead, the curvature envelope downstream of the coolant holes plays a significant role on the performance of film cooling for cylindrical holes.

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References

Bogard, D. G., and Thole, K. A., 2006, “Gas Turbine Film Cooling,” J. Propul. Power, 22, pp. 249–270. [CrossRef]
Ito, S., Goldstein, R. J., and Eckert, E. R. G., 1978, “Film Cooling of a Gas Turbine Blade,” ASME J. Eng. Power, 100, pp. 476–481. [CrossRef]
Schwarz, S. G., Goldstein, R. J., and Eckert, E. R. G., 1991, “The Influence of Curvature on Film Cooling Performance,” ASME J. Turbomach., 113, pp. 472–478. [CrossRef]
Goldstein, R. J., and Stone, L. D., 1997, “Row-of-Holes Film Cooling of a Convex and a Concave Wall at Low Injection Angles,” ASME J. Turbomach., 119, pp. 574–579. [CrossRef]
Hylton, L. D., Milhec, M. S., Turner, E. R., Nealy, D. A., and York, R. E., 1983, “Analytical and Experimental Evaluation of the Heat Transfer Distribution Over the Surface of Turbine Vanes,” NASA Contractor Report 168015.
Dees, J. E., Ledezma, G. A., Bogard, D. G., Laskowski, G. M., and Tolpadi, A. K., 2012, “Experimental Measurements and Computational Predictions for an Internally Cooled Simulated Turbine Vane,” ASME J. Turbomach., 134(6), p. 061003. [CrossRef]
Pichon, Y., 2009, “Turbulence Field Measurements for the Large Windtunnel,” The University of Texas at Austin, Austin, TX, TTCRL Internal Report 2009.
Ethridge, M. I., Cutbirth, J. M., and Bogard, D. G., 2001, “Scaling of Performance for Varying Density Ratio Coolants on an Airfoil With Strong Curvature and Pressure Gradient Effects,” ASME J. Turbomach., 123, pp. 231–237. [CrossRef]
Dees, J. E., Bogard, D. G., Ledezma, G. A., and Laskowski, G. M., 2011, “Overall and Adiabatic Effectiveness Values on a Scaled Up, Simulated Gas Turbine Vane: Part I—Experimental Measurements,” ASME Paper No. GT2011-46612. [CrossRef]
Moffat, R. J., 1985, “Using Uncertainty Analysis in the Planning of an Experiment,” ASME J. Fluids Eng., 107, pp. 173–178. [CrossRef]

Figures

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Fig. 1

TTCRL wind tunnel and test section schematic

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Fig. 2

Measured pressure distribution compared to the predicted infinite cascade of Dees et al. [6]

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Fig. 3

Schematic of coolant flow loop

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Fig. 4

Schematic of internal cooling flow path

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Fig. 5

Contour plots of adjacent holes, indicating near-uniform lateral performance. I = 0.25 (a) and I = 0.88 (b). Data taken from Case 5.

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Fig. 6

Hole locations along the vane of each test case

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Fig. 7

Spatially averaged adiabatic effectiveness at three different surface curvature values different surface curvature values: r = 52 mm (high curvature), 67 mm (moderate curvature), and > 1000 mm (low curvature)

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Fig. 8

Laterally averaged adiabatic effectiveness for various I; Case 1: 2r/d = 28, d = 3.73 mm, s/C = 0.24, DR = 1.2

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Fig. 9

Contour plots of adiabatic effectiveness for various I; Case 1: 2r/d = 28, d = 3.73 mm, s/C = 0.24, DR = 1.2

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Fig. 10

Laterally averaged adiabatic effectiveness for various I; Case 2: 2r/d = 28, d = 5.37 mm, s/C = 0.29, DR = 1.2

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Fig. 11

Contour plots of adiabatic effectiveness for various I; Case 2: 2r/d = 28, d = 5.37 mm, s/C = 0.30, DR = 1.2

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Fig. 12

Laterally averaged adiabatic effectiveness for various I; Case 3: 2r/d = 40, d = 3.73 mm, s/C = 0.30, DR = 1.2

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Fig. 13

Contour plots of adiabatic effectiveness for various I; Case 3: 2r/d = 40, d = 3.73 mm, s/C = 0.28, DR = 1.2

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Fig. 14

Comparisons of spatially averaged adiabatic effectiveness for matched 2r/d = 28 (Cases 1 and 2) and matched r = 75 (Cases 2 and 3)

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Fig. 15

Laterally averaged adiabatic effectiveness for Cases 1–3 for (a) I = 0.20 and (b) I = 0.85

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Fig. 16

Laterally averaged adiabatic effectiveness for various I; Case 4: 2r/d = 40, d = 3.34 mm, s/C = 0.28, DR = 1.2

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Fig. 17

Contour plots of adiabatic effectiveness for various I; Case 4: 2r/d = 40, d = 3.34, s/C = 0.28, DR = 1.2

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Fig. 18

Laterally averaged adiabatic effectiveness for various I; Case 5: 2r/d = 40, d = 3.34 mm, s/C = 0.16, DR = 1.2

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Fig. 19

Contour plots of adiabatic effectiveness for various I; Case 5: 2r/d = 40, d = 3.34 mm, s/C = 0.16, DR = 1.2

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Fig. 20

Spatially averaged effectiveness over x/d = 0 to 24, of upstream and downstream holes

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Fig. 21

Lateral distribution of adiabatic effectiveness at x/d = 10 and I ≈ 0.23

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