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Research Papers

Improved Film Cooling Effectiveness With a Round Film Cooling Hole Embedded in a Contoured Crater

[+] Author and Article Information
Prasad Kalghatgi

Department of Mechanical Engineering,
Center for Turbine Innovation
and Energy Research,
Louisiana State University,
Baton Rouge, LA 70803
e-mail: pkalgh1@tigers.lsu.edu

Sumanta Acharya

Department of Mechanical Engineering,
Center for Turbine Innovation
and Energy Research,
Louisiana State University,
Baton Rouge, LA 70803
e-mail: acharya@me.lsu.edu

1Corresponding author.

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received October 25, 2014; final manuscript received March 29, 2015; published online June 9, 2015. Assoc. Editor: Ronald Bunker.

J. Turbomach 137(10), 101006 (Jun 09, 2015) (10 pages) Paper No: TURBO-14-1279; doi: 10.1115/1.4030395 History: Received October 25, 2014

Studies of film cooling holes embedded in craters and trenches have shown significant improvements in the film cooling performance. In this paper, a new design of a round film cooling hole embedded in a contoured crater is proposed for improved film cooling effectiveness over existing crater designs. The proposed design of the contour aims to generate a pair of vortices that counter and diminish the near-field development of the main kidney-pair vortex generated by the film cooling jet. With a weakened kidney-pair vortex, the coolant jet is expected to stay closer to the wall, reduce mixing, and therefore increase cooling effectiveness. In the present study, the performance of the proposed contoured crater design is evaluated for depth between 0.2D and 0.75D. A round film cooling hole with a 35 deg inclined short delivery tube (l/D = 1.75), freestream Reynolds number ReD = 16,000, and density ratio of coolant to freestream fluid ρj = 2.0 is used as the baseline case. Hydrodynamic and thermal fields for all cases are investigated numerically using large eddy simulation (LES) technique. The baseline case results are validated with published experimental data. The performance of the new crater design for various crater depths and blowing ratios are compared with the baseline case. Results are also compared with other reported crater designs with similar flow conditions and crater depth. Performance improvement in cooling effectiveness of over 100% of the corresponding baseline case is observed for the contoured crater.

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References

Figures

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Fig. 1

Schematic of the baseline geometry

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Fig. 3

Streamwise mean and RMS velocity profiles (▲U/U0(exp),▼U'/U0(exp)),-U/U0(sim),--U'/U0(sim)

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Fig. 4

Wall normal mean and RMS velocity profiles (▼V/U0(exp),▲V'/U0(exp)),-V/U0(sim),--V'/U0(sim)

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Fig. 5

Validation of adiabatic film cooling effectiveness

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Fig. 6

Validation of adiabatic film cooling effectiveness for 0.5D round crater [9]

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Fig. 7

Schematic of the contoured crater

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Fig. 8

Computer-aided design model of the contoured crater and schematic of expected flow features

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Fig. 9

Centerline film cooling effectiveness for the baseline case and the various contoured craters for B.R. = 1.0

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Fig. 10

Laterally averaged film cooling effectiveness for the baseline case and the various contoured craters for B.R. = 1.0

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Fig. 11

Adiabatic film cooling effectiveness on the film cooled wall for the baseline case and V-contoured craters of different depths for B.R. = 1.0

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Fig. 12

Heat transfer coefficient ratio h/h0 on the film cooled surface for the baseline case and V-contoured craters of different depths for B.R. = 1.0

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Fig. 13

Laterally averaged heat transfer coefficient ratio (h¯/h0) for the baseline case and the various contoured craters for B.R. = 1.0

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Fig. 14

Effect of blowing ratio on η¯ for baseline case and 0.75D crater

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Fig. 15

Contours of η for baseline and 0.75D crater at various blowing ratios

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Fig. 16

Comparison of laterally averaged effectiveness improvements over baseline case for conventional crater, trenches, and contoured crater design (B.R. = 1.0)

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Fig. 17

Streamlines and temperature (T*) contours on section x = 0.5D for baseline case (B.R. = 1.0)

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Fig. 18

Streamlines and temperature (T*) contours on section x = 0.5D for 0.2D crater case (B.R. = 1.0)

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Fig. 19

Streamlines and temperature (T*) contours on section x = 0.5D for 0.4D crater case (B.R. = 1.0)

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Fig. 20

Streamlines and temperature (T*) contours on section x = 0.5D for 0.75D crater case (B.R. = 1.0)

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Fig. 21

Temperature (T*) contours on spanwise midsection (B.R. = 1.0)

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Fig. 22

Time-averaged flow structures 0.2D case

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Fig. 23

Time-averaged flow structures 0.4D case

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Fig. 24

Time-averaged flow structures 0.75D case

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Fig. 25

Tornado structures 0.75D case

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