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Research Papers

Numerical Study on the Effects of Freestream Turbulence on Antivortex Film Cooling Design at High Blowing Ratio

[+] Author and Article Information
Timothy W. Repko, Andrew C. Nix

Department of Mechanical and
Aerospace Engineering,
West Virginia University,
Morgantown, WV 26505

Can Uysal

Department of Mechanical and
Aerospace Engineering,
West Virginia University,
Morgantown, WV 26505
e-mail: andrew.nix@mail.wvu.edu

James D. Heidmann

Turbomachinery and Heat Transfer Branch,
NASA Glenn Research Center,
Cleveland, OH 44135
e-mail: heidmann@nasa.gov

Contributed by the Heat Transfer Division of ASME for publication in the JOURNAL OF THERMAL SCIENCE AND ENGINEERING APPLICATIONS. Manuscript received December 21, 2015; final manuscript received August 4, 2016; published online November 8, 2016. Assoc. Editor: Srinath V. Ekkad.This work is in part a work of the U.S. Government. ASME disclaims all interest in the U.S. Government's contributions.

J. Thermal Sci. Eng. Appl 9(1), 011013 (Nov 08, 2016) (12 pages) Paper No: TSEA-15-1359; doi: 10.1115/1.4034851 History: Received December 21, 2015; Revised August 04, 2016

An advanced, high-effectiveness film cooling design, the antivortex hole (AVH) has been investigated by several research groups and shown to mitigate or counter the vorticity generated by conventional holes and increase film effectiveness at high blowing ratios and low freestream turbulence levels. The effects of increased turbulence on an AVH geometry were previously investigated in a preliminary steady computational fluid dynamics (CFD) study by Hunley et al. on the film effectiveness and net heat flux reduction (NHFR) at high blowing ratio. The current paper presents the results of an extended numerical parametric study, which attempts to separate the effects of turbulence intensity and length scale on film cooling performance of the AVH concept at high blowing ratio (2.0) and density ratio (2.0). In this extended study, steady Reynolds-averaged Navier–Stokes (RANS) analysis was performed with turbulence intensities of 5, 10, and 20% and length scales based on cooling hole diameter of Λx/dm = 1, 3, and 6. Increasing turbulence intensity was shown to increase the centerline, span-averaged, and area-averaged adiabatic film cooling effectiveness and NHFR. Larger turbulent length scales in the steady RANS analysis were shown to have little to no effect on the centerline, span-averaged, and area-averaged adiabatic film cooling effectiveness and NHFR at lower turbulence levels, but moderate effect at the highest turbulence levels investigated. Heat transfer results were in good agreement with the findings from adiabatic cases from previous work. Unsteady RANS results also provided supplementary flow visualization for the AVH film cooling flow under varying turbulence levels.

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References

Figures

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Fig. 3

Grid and setup of computational domain (modified from Ref. [8])

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Fig. 2

Generic orthographic projections of the AVH [8]

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Fig. 1

Illustration of counter rotating vortex (CRV) [3]

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Fig. 4

Mesh resolution near AVH geometry (structured)

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Fig. 5

Grid independence study comparing centerline effectiveness [22]

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Fig. 6

Centerline effectiveness for a conventional hole compared with experimental data

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Fig. 7

Span-averaged effectiveness for a conventional hole compared with experimental data

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Fig. 8

Contours of adiabatic film cooling effectiveness

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Fig. 9

Centerline effectiveness at constant length scale (a–c) and turbulence intensity (d–f)

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Fig. 10

Span-averaged effectiveness at constant length scale (a–c) and turbulence intensity (d–f)

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Fig. 13

Contour plots of RANS and URANS predictions of adiabatic effectiveness [29]

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Fig. 14

Isosurface of dimensionless temperature for turbulence intensities of 5, 10, and 20% [22]

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Fig. 11

Span-averaged dimensionless heat transfer coefficient at constant length scale (a–c) and turbulence intensity (d–f)

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Fig. 12

Span-averaged NHFR at constant length scale (a–c) and turbulence intensity (d–f)

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Fig. 15

Lateral spread of the coolant flow increases as the turbulence intensity is increased [22]

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