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Research Papers

Direct Experimental Measurements of Heat Transfer Coefficient Augmentation Due to Approach Flow Effects

[+] Author and Article Information
Joshua B. Anderson

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

David G. Bogard

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

Thomas E. Dyson

GE Global Research,
Niskayuna, NY 12309
e-mail: dyson@ge.com

Zachary Webster

GE Aviation,
Evendale, OH 45215
e-mail: zachary.webster@ge.com

1Present address: Williams International, Pontiac, MI 48341.

2Corresponding author.

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received November 16, 2018; final manuscript received December 3, 2018; published online January 16, 2019. Editor: Kenneth Hall.

J. Turbomach 141(3), 031011 (Jan 16, 2019) (8 pages) Paper No: TURBO-18-1331; doi: 10.1115/1.4042210 History: Received November 16, 2018; Revised December 03, 2018

Film cooling can have a significant effect on the heat transfer coefficient (HTC) between the overflowing freestream gas and the underlying surface. This study investigated the influence of approach flow characteristics, including the boundary layer thickness and character (laminar and turbulent), as well as the approach flow Reynolds number, on the HTC. The figure of merit for this study was the HTC augmentation, that is, the ratio of HTCs for a cooled versus uncooled surface. A heated foil surface provided a known heat flux, allowing direct measurement of HTC and augmentation. The foil was placed both upstream and downstream of the film cooling holes, in order to generate an approaching thermal boundary layer, as representative of actual engine conditions. High-resolution IR thermography provided spatially resolved HTC augmentation data. An open-literature shaped-hole design was used, known as the 7-7-7 hole, in order to compare with existing results in the literature. A variety of blowing conditions were tested from M =0.5 to 3.0. Two elevated density ratios of DR = 1.20 and DR = 1.80 were used. The results indicated that turbulent boundary layer thickness had a modest effect on HTC augmentation, whereas a very high level of augmentation was observed for a laminar approach boundary layer. The presence of upstream heating greatly increased the HTC augmentation in the near-hole region, although these effects died out by 10–15 diameters from the holes.

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References

Bogard, D. , and Thole, K. , 2006, “ Gas Turbine Film Cooling,” J. Propul. Power, 22(2), pp. 249–270. [CrossRef]
Eckert, E. , 1970, “ Gas-to-Gas Film Cooling,” J. Eng. Phys., 19(3), pp. 1091–1101. [CrossRef]
Baldauf, S. , Scheurlen, M. , Schulz, A. , and Wittig, S. , 2002, “ Heat Flux Reduction From Film Cooling and Correlation of Heat Transfer Coefficients From Thermographic Measurements at Enginelike Conditions,” ASME J. Turbomach., 124(4), pp. 699–709. [CrossRef]
Gritsch, M. , Schulz, A. , and Wittig, S. , 2000, “ Film-Cooling Holes With Expanded Exits: Near-Hole Heat Transfer Coefficients,” Int. J. Heat Fluid Flow, 21(2), pp. 146–155. [CrossRef]
Bonanni, L. , Bacchini, B. , Tarchi, L. , Maritano, M. , and Traverso, S. , 2010, “ Heat Transfer Performance of Fan-Shaped Film Cooling Holes—Part I: Experimental Analysis,” ASME Paper No. GT2010-22808.
Boyd, E. , McClintic, J. , Chavez, K. , and Bogard, D. , 2017, “ Direct Measurement of Heat Transfer Coefficient Augmentation at Multiple Density Ratios,” ASME J. Turbomach., 139(1), p. 011005. [CrossRef]
Saumweber, C. , and Schulz, A. , 2012, “ Free-Stream Effects on the Cooling Performance of Cylindrical and Fan-Shaped Cooling Holes,” ASME J. Turbomach., 134(6), p. 061007. [CrossRef]
Bunker, R. , 2005, “ A Review of Shaped Hole Turbine Film Cooling Technology,” ASME J. Heat Transfer, 127(4), pp. 441–453. [CrossRef]
Anderson, J. , Wilkes, E. , McClintic, J. , and Bogard, D. , 2016, “ Effects of Freestream Mach Number, Reynolds Number and Boundary Layer Thickness on Film Cooling Effectiveness of Shaped Holes,” ASME Paper No. GT2016-56152.
Harrison, K. , Dorrington, J. , Dees, J. , Bogard, D. , and Bunker, R. , 2009, “ Turbine Airfoil Net Heat Flux Reduction With Cylindrical Holes Embedded in a Transverse Trench,” ASME J. Turbomach., 131(1), p. 011012.
Anderson, J. , McClintic, J. , Bogard, D. , Dyson, T. , and Webster, Z. , 2017, “ Freestream Flow Effects on Film Cooling Effectiveness and Heat Transfer Coefficient Augmentation for Compound-Angle Shaped Holes,” ASME Paper No. GT2017-64853.
McClintic, J. , Klavetter, S. , Anderson, J. , Winka, J. , Bogard, D. , Dees, J. , Laskowski, G. , and Briggs, R. , 2015, “ The Effect of Internal Cross-Flow on the Adiabatic Effectiveness of Compound Angle Film Cooling Holes,” ASME J. Turbomach., 137(7), p. 071006. [CrossRef]
Schroeder, R. , and Thole, K. , 2014, “ Adiabatic Effectiveness Measurements for a Baseline Shaped Film Cooling Hole,” ASME Paper No. GT2014-25992.
Kays, W. , Crawford, M. , and Wiegland, B. , 2003, Convective Heat and Mass Transfer, McGraw-Hill, New York.
Moffat, R. , 1985, “ Using Uncertainty Analysis in the Planning of an Experiment,” ASME J. Fluids Eng., 107(2), pp. 173–178. [CrossRef]
Anderson, J. , Boyd, E. , and Bogard, D. , 2015, “ Experimental Investigation of Coolant-to-Mainstream Scaling Parameters With Cylindrical and Shaped Film Cooling Holes,” ASME Paper No. GT2015-43072.

Figures

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Fig. 1

Diagram of the test coupon and heat flux plates

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Fig. 2

Laterally averaged distributions of h0 (laminar boundary layer) for the upstream and downstream heat flux plates; compared to the correlation of Kays et al. [14]

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Fig. 3

Comparison of 7-7-7 adiabatic effectiveness with results of the present study with those of Boyd et al. [6], Anderson et al. [16], and Schroeder and Thole [13]. Tu = 4.5–5.5% and δ/D =1.1–1.5.

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Fig. 4

Spatial contours of η for the baseline condition (case 1); Tu = 4.5%, δ/D =1.7, and DR = 1.20

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Fig. 5

Spatial contours of hf,norm for the baseline condition (case 1); Tu = 4.5%, δ/D =1.7, and DR = 1.20; US plate active

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Fig. 6

Laterally averaged distributions of η and hf,norm for the baseline freestream conditions (case 1); Tu = 4.5%, δ/D =1.7, and DR = 1.20, with upstream plate active

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Fig. 7

Spatial contours of hf,norm for a thick turbulent boundary layer (case 2); Tu = 4.5%, δ/D =4.0, and DR = 1.20; US plate active

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Fig. 8

Laterally averaged hf,norm for a thick turbulent boundary layer (case 2); Tu = 4.5%, δ/D =3.5, and DR = 1.20; US plate active

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Fig. 9

Spatial contours of hf,norm for injection into a laminar boundary layer (case 3); Tu = 0.5%, δ/D =0.4, and DR = 1.20

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Fig. 10

Distributions of laterally averaged hf,norm¯ for injection into a laminar boundary layer (case 3); Tu = 0.5%, δ/D =0.4, and DR = 1.20

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Fig. 11

Spatial contours of hf,norm comparing effects of upstream heat addition (cases 1 and 4); Tu = 4.5%, δ/D =1.7, and DR = 1.20

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Fig. 12

Spatial contours of hf,norm comparing effects of upstream heat addition (cases 3 and 5); Tu = 0.5%, δ/D =0.5, and DR = 1.20, laminar boundary layer

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Fig. 13

Effect of upstream heat addition on laterally averaged hf,norm¯ for a laminar boundary layer (right, δ/D =0.4 and Tu = 0.5%) and turbulent boundary layer (left, δ/D =1.7 and Tu = 4.5%); DR = 1.20

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Fig. 14

Spatial contours of hf,norm showing the effect of DR variation between DR = 1.2 and 1.8 (case 6); δ99/D =4.0 and Tu = 4.5% (with upstream heating)

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Fig. 15

Laterally averaged hf,norm¯ between DR = 1.2 and 1.8 (cases 2 and 6); δ99/D =4.0 and Tu = 4.5%; US plate active

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