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Research Papers

Detailed Heat Transfer Distributions in Engine Similar Cooling Channels for a Turbine Rotor Blade With Different Rib Orientations

[+] Author and Article Information
Srinath V. Ekkad

e-mail: sekkad@vt.edu
Mechanical Engineering Department,
Virginia Tech,
Blacksburg, VA, 24061

Veera Rajendran

Rolls-Royce Corporation,
Indianapolis, IN, 46214

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received June 27, 2011; final manuscript received August 17, 2011; published online October 31, 2012. Editor: David Wisler.

J. Turbomach 135(1), 011034 (Oct 31, 2012) (8 pages) Paper No: TURBO-11-1094; doi: 10.1115/1.4006387 History: Received June 27, 2011; Revised August 17, 2011

Detailed Nusselt number distributions are presented for a gas turbine engine similar internal channel geometry used for cooling a modern first stage rotor blade. The cooling design has one leading edge channel and a three-pass channel that covers the rest of the blade. The simulated model, generated from the midspan section of an actual cooling circuit, was studied for wall heat transfer coefficient measurements using the transient liquid crystal technique. The model wall inner surfaces were sprayed with thermochromic liquid crystals, and a transient test was used to obtain the local heat transfer coefficients from the measured color change. Results are presented for a nominal channel inlet leading edge channel Reynolds number of 10,700 and a channel inlet three-pass channel Reynolds number of 25,500. Detailed heat transfer measurements are presented for the simulated leading edge, first pass, second pass and third pass interior walls for different rib configurations. The channels were studied for smooth, 90 deg ribs, and angled ribs geometries in addition to ribs on the divider walls between adjacent passages. Overall pressure drop measurements were also obtained for each passage. Some of these results are compared with the predicted heat transfer from standard correlations used in design practices. Results show very complicated heat transfer behavior in these realistic channels compared to results obtained in simplistic geometry channels from published studies. In some cases, the Nusselt numbers predicted by correlations are 50–60% higher than obtained from the current experiments.

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References

Han, J. C., 1984, “Heat Transfer and Friction in Channels with Two Opposite Rib-Roughened Walls,” ASME J. Heat Transfer, 106, pp. 774–781. [CrossRef]
Han, J. C., 1988, “Heat Transfer and Friction Characteristics in Rectangular Channels With Rib Turbulators,” ASME J. Transfer, 110, pp. 321–328. [CrossRef]
Han, J. C., Zhang, Y. M., and Lee, C. P., 1991, “Augmented Heat Transfer in Square Channels With Parallel, Crossed, and V-Shaped Ribs,” ASME J. Heat Transfer, 113, pp. 590–596. [CrossRef]
Zhang, Y. M., Gu, W. Z., and Han, J. C., 1994, “Augmented Heat Transfer in Triangular Ducts With Full and Partial Ribbed Walls,” AIAA J. Thermophys. Heat Transfer, 8, pp. 574–579. [CrossRef]
Taslim, M. E., Li, T., and Spring, S. D., 1997, “Measurements of Heat Transfer Coefficients and Friction Factors in Rib-Roughened Channels Simulating Leading Edge Cavities of a Modern Turbine Blade,” ASME J. Turbomach., 119, pp. 601–609. [CrossRef]
Ekkad, S. V., and Han, J. C., 1997, “Detailed Heat Transfer Distributions in Two-Pass Square Channels With Rib Turbulators,” Int. J. Heat Mass Transfer, 40(11) pp. 2525–2537. [CrossRef]
Han, J. C., Dutta, S., and Ekkad, S. V., 2001, Gas Turbine Heat Transfer and Cooling Technology, Taylor & Francis, New York.
Poser, R., Von Wolfersdorf, J., Lutum, E., and Semmler, K., 2008, “Performing Heat Transfer Experiments in Blade Cooling Circuits Using a Transient Technique With Thermochromic Liquid Crystals,” ASME Turbo Expo 2008: Power for Land, Sea, and Air (GT2008), Berlin, June 9–13, ASME Paper No. GT2008-50364. 1 [CrossRef]
Esposito, E., Ekkad, S. V., Kim, Y. W., and Dutta, P., 2009, “Novel Jet Impingement Cooling Geometry for Combustor Liner Backside Cooling,” ASME J. Therm. Sci. Eng. Appl., 1, p. 021001. [CrossRef]
Ekkad, S. V., and Han, J. C., 2000, “A Transient Liquid Crystal Thermography Technique for Gas Turbine Heat Transfer Measurements,” Meas. Sci. Technol.11, pp. 957–968. [CrossRef]
Kline, S. J., McClintock, F. A., 1953, “Describing Uncertainties in Single Sample Experiments,” Mech. Eng., 75, pp. 3–8.
Ekkad, S. V., Huang, Y., and Han, J. C., 1998, “Detailed Heat Transfer Distributions in Two-Pass Square Channels With Rib Turbulators and Bleed Holes,” Int. J. Heat Mass Transfer, 41, pp. 3781–3791. [CrossRef]

Figures

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Fig. 1

Experimental set up

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Fig. 2

Step change in mainstream temperature obtained from mesh heater response

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Fig. 3

(a) Actual channel geometry; (b) simplified channel geometry

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Fig. 4

(a) Leading edge channel geometry; (b) triple pass channel geometry

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Fig. 5

Rib arrangements studied

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Fig. 6

Detailed heat transfer (Nu) distributions for all channels with Configuration (C)

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Fig. 7

Spanwise averaged Nusselt number for the leading edge channel

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Fig. 8

Spanwise averaged Nusselt number distributions for the first pass of the triple pass channel

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Fig. 9

Spanwise averaged Nusselt number distributions for the second pass of the triple pass channel

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Fig. 10

Spanwise averaged Nusselt number distributions for the third pass of the triple pass channel

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