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Research Papers

Flow Physics of Diffused-Exit Film Cooling Holes Fed by Internal Crossflow

[+] Author and Article Information
John W. McClintic

Walker Department of Mechanical Engineering,
The University of Texas at Austin,
204 E. Dean Keeton Street,
Austin, TX 78712
e-mail: johnwmcclintic@gmail.com

Dale W. Fox

Walker Department of Mechanical Engineering,
The University of Texas at Austin,
204 E. Dean Keeton Street,
Austin, TX 78712
e-mail: Dale.Fox@utexas.edu

Fraser B. Jones

Walker Department of Mechanical Engineering,
The University of Texas at Austin,
204 E. Dean Keeton Street,
Austin, TX 78712
e-mail: me.fbjones@gmail.com

David G. Bogard

Walker Department of Mechanical Engineering,
The University of Texas at Austin,
204 E. Dean Keeton Street,
Austin, TX 78712
e-mail: dbogard@mail.utexas.edu

Thomas E. Dyson

GE Global Research Center,
1 Research Circle,
Schenectady, NY 12309
e-mail: dyson@ge.com

Zachary D. Webster

GE Aviation,
1 Neumann Way,
Cincinnati, OH 45125
e-mail: Zachary.Webster@ge.com

1Present address: Honeywell Aerospace, Pheonix, AZ 85034.

2Corresponding author.

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received November 9, 2018; final manuscript received November 26, 2018; published online January 16, 2019. Editor: Kenneth Hall.

J. Turbomach 141(3), 031010 (Jan 16, 2019) (9 pages) Paper No: TURBO-18-1326; doi: 10.1115/1.4042166 History: Received November 09, 2018; Revised November 26, 2018

Internal crossflow, or internal flow that is perpendicular to the overflowing mainstream, reduces film cooling effectiveness by disrupting the diffusion of coolant at the exit of axial shaped holes. Previous experimental investigations have shown that internal crossflow causes the coolant to bias toward one side of the diffuser and that the severity of the biasing scales with the inlet velocity ratio, VRi, or the ratio of crossflow velocity to the jet velocity in the metering section of the hole. It has been hypothesized and computationally predicted that internal crossflow produces an asymmetric swirling flow within the hole that causes the coolant to bias in the diffuser and that biasing contributes to ingestion of hot mainstream gas into the hole, which is undesirable. However, there are no experimental measurements as of yet to confirm these predictions. In the present study, in- and near-hole flow field and thermal field measurements were performed to investigate the flow structures and mainstream ingestion for a standard axial shaped hole fed by internal crossflow. Three different inlet velocity ratios of VRi = 0.24, 0.36, and 0.71 were tested at varying injection rates. Measurements were made in planes normal to the nominal direction of coolant flow at the outlet plane of the hole and at two downstream locations—x/d =0 and 5. The predicted swirling structure was observed for the highest inlet velocity ratio and flow within the hole was shown to scale with VRi. Ingestion within the diffuser was significant and also scaled with VRi. Downstream flow and thermal fields showed that increased biasing contributed to more severe jet detachment and coolant dispersion away from the surface.

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References

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Figures

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Fig. 1

Near-hole contours of η, measured in Ref. [6]

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Fig. 2

Schematic of test section and channel

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Fig. 3

7-7-7 film cooling hole geometry

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Fig. 4

Location of measurement planes for thermal and velocity field measurements

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Fig. 5

Repeatability of the thermal field measurement for VRi = 0.24, VR = 0.83, x/d = 0, and z/d = −0.33

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Fig. 6

Repeatability of in-hole PIV measurements for VRi = 0.71 and VR = 0.56; (a) and (b) are from different experiments

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Fig. 7

Vector plots of in-hole mean velocity for all conditions tested overlaid on contours of in-plane turbulence intensity

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Fig. 8

Contours of normalized temperature in the yz plane at x/d = −2 for all conditions tested

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Fig. 9

Vector plots of mean velocity overlaid on contours of normalized mean temperature for VRi = 0.24

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Fig. 10

Vector plots of mean velocity overlaid on contours of normalized mean temperature for VRi = 0.36

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Fig. 11

Vector plots of mean velocity overlaid on contours of normalized mean temperature for VRi = 0.71

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