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Research Papers

Full-Coverage Film Cooling: Film Effectiveness and Heat Transfer Coefficients for Dense Hole Arrays at Different Hole Angles, Contraction Ratios, and Blowing Ratios

[+] Author and Article Information
Phil Ligrani

e-mail: pligrani@slu.edu

Matt Goodro

Graduate Student
e-mail: robert.goodro@us.af.mil
Department of Engineering Science,
University of Oxford,
Oxford, OX1 3PJ, UK

Mike Fox

Senior Consulting Engineer

Hee-Koo Moon

Heat Transfer Manager
Solar Turbines, Inc.,
San Diego, CA 92101

1Corresponding author.

2Present address: Oliver L. Parks Endowed Chair, Director of Graduate Programs, Professor of Aerospace and Mechanical Engineering. Parks College of Engineering, Aviation and Technology, Saint Louis University, 3450 Lindell Boulevard, McDonnell Douglas Hall Room 1033A, St. Louis, MO 63103.

3Present address: Mechanical Engineer, Air Force Nuclear Weapons Center, Hill Air Force Base, UT 84056.

Contributed by the Heat Transfer Division of ASME for publication in the Journal of Heat Transfer. Manuscript received March 23, 2012; final manuscript received October 16, 2012; published online February 14, 2013. Assoc. Editor: Frank Cunha.

J. Heat Transfer 135(3), 031707 (Feb 14, 2013) (14 pages) Paper No: HT-12-1130; doi: 10.1115/1.4007981 History: Received March 23, 2012; Revised October 16, 2012

Experimental results are presented for a full-coverage film cooling arrangement which simulates a portion of a gas turbine engine, with appropriate streamwise static pressure gradient. The test surface utilizes varying blowing ratio (BR) along the length of the contraction passage which contains the cooling hole arrangement. For the different experimental conditions examined, film cooling holes are sharp-edged and streamwise inclined either at 20 deg or 30 deg with respect to the liner surface. The film cooling holes in adjacent streamwise rows are staggered with respect to each other. Data are provided for turbulent film cooling, contraction ratios of 1, 3, 4, and 5, blowing ratios (at the test section entrance) of 2.0, 5.0, and 10.0, coolant Reynolds numbers Refc of 10,000–12,000, freestream temperatures from 75 °C to 115 °C, a film hole diameter of 7 mm, and density ratios from 1.15 to 1.25. Nondimensional streamwise and spanwise film cooling hole spacings, X/D and Y/D, are 6, and 5, respectively. When the streamwise hole inclination angle is 20 deg spatially averaged and line-averaged adiabatic effectiveness values at each x/D location are about the same as the contraction ratio varies between 1, 3, and 4, with slightly higher values at each x/D location when the contraction ratio Cr is 5. For each contraction ratio, there is a slight increase in effectiveness when the blowing ratio is increased from 2.0 to 5.0 but there is no further substantial improvement when the blowing ratio is increased to 10.0. Overall, line-averaged and spatially averaged-adiabatic film effectiveness data, and spatially averaged heat transfer coefficient data are described as they are affected by contraction ratio, blowing ratio, hole angle α, and streamwise location x/D. For example, when α = 20 deg, the detrimental effects of mainstream acceleration are apparent since heat transfer coefficients for contraction ratios Cr of 3 and 5 are often higher than values for Cr = 1, especially for x/D > 100.

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References

Figures

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Fig. 1

Film cooling wind tunnel test facility

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Fig. 2

Film cooling test section. + denotes measurement location for mainstream static pressure.

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Fig. 3

Film cooling test plate for X/D = 6, Y/D = 5 and hole angle 20 deg. (a) Test section dimensions and layout, where all dimensions are given in millimeters. (b) Test section coordinate system.

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Fig. 4

Example of variation of local surface heat flux with surface temperature for one test surface location during a typical transient test

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Fig. 5

Blowing ratio variation with x/D for different contraction ratios, calculated on the basis of static pressure ratios

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Fig. 6

(a) Variation of acceleration parameter through the test section for contraction ratios Cr of 1, 3, 4, and 5. (b) Variation of ratio of coolant mass flow rate to mainstream mass flow rate for X/D = 6, with Y/D = 5, a blowing ratio BR of 5.0 for contraction ratios Cr of 1, 3, 4, and 5.

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Fig. 7

Spatially resolved, local adiabatic effectiveness at different blowing ratios for hole spacings X/D = 6, Y/D = 5, streamwise hole inclination angle of 20 deg, and contraction ratio Cr = 1, for (a) constant x/D = 24 and (b) constant y/D = 0

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Fig. 8

Spatially resolved, local adiabatic effectiveness at different blowing ratios for hole spacings X/D = 6, Y/D = 5, streamwise hole inclination angle of 20 deg, and contraction ratio Cr = 3, for (a) constant x/D = 24 and (b) constant y/D = 0

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Fig. 9

Spatially resolved, local adiabatic effectiveness at different blowing ratios for hole spacings X/D = 6, Y/D = 5, streamwise hole inclination angle of 20 deg, and contraction ratio Cr = 4, for (a) constant x/D = 24 and (b) constant y/D = 0

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Fig. 10

Spatially resolved, local adiabatic effectiveness at different blowing ratios for hole spacings X/D = 6, Y/D = 5, streamwise hole inclination angle of 20 deg, and contraction ratio Cr = 5, for (a) constant x/D = 24 and (b) constant y/D = 0

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Fig. 11

Line-averaged adiabatic film effectiveness at a blowing ratio BR of 2.0 for hole spacings X/D = 6 and Y/D = 5, streamwise hole inclination angle of 20 deg, and contraction ratios Cr of 1, 3, 4, and 5, with line-averaging over y/D

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Fig. 12

Line-averaged adiabatic film effectiveness at a blowing ratio BR of 10.0 for hole spacings X/D = 6 and Y/D = 5, streamwise hole inclination angle of 20 deg, and contraction ratios Cr of 1, 3, 4, and 5, with line-averaging over y/D

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Fig. 13

Variations of spatially averaged-adiabatic film effectiveness at different contraction ratios Cr for blowing ratio BR of 2.0, streamwise hole inclination angle of 20 deg, streamwise hole spacing X/D of 6, and spanwise hole spacing Y/D of 5

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Fig. 14

Variations of spatially averaged-adiabatic film effectiveness at different contraction ratios Cr for blowing ratio BR of 5.0, streamwise hole inclination angle of 20 deg, streamwise hole spacing X/D of 6, and spanwise hole spacing Y/D of 5

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Fig. 15

Variations of spatially averaged-adiabatic film effectiveness at different contraction ratios Cr for blowing ratio BR of 10.0, streamwise hole inclination angle of 20 deg, streamwise hole spacing X/D of 6, and spanwise hole spacing Y/D of 5

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Fig. 16

Spatially averaged heat transfer coefficients at different contraction ratios Cr for blowing ratio BR of 2.0, streamwise hole inclination angle of 20 deg, streamwise hole spacing X/D of 6, and spanwise hole spacing Y/D of 5

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Fig. 17

Spatially averaged heat transfer coefficients at different contraction ratios Cr for blowing ratio BR of 5.0, streamwise hole inclination angle of 20 deg, streamwise hole spacing X/D of 6, and spanwise hole spacing Y/D of 5

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Fig. 18

Spatially averaged heat transfer coefficients at different contraction ratios Cr for blowing ratio BR of 10.0, streamwise hole inclination angle of 20 deg, streamwise hole spacing X/D of 6, and spanwise hole spacing Y/D of 5

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Fig. 19

Spatially resolved, local adiabatic effectiveness at different blowing ratios for hole spacings X/D = 6, Y/D = 5, streamwise hole inclination angle of 30 deg, and contraction ratio Cr = 1, for (a) constant x/D = 24 and (b) constant y/D = 0

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Fig. 20

Spatially resolved, local adiabatic effectiveness at different blowing ratios for hole spacings X/D = 6, Y/D = 5, streamwise hole inclination angle of 30 deg, and contraction ratio Cr = 4, for (a) constant x/D = 24 and (b) constant y/D = 0

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Fig. 21

Line-averaged adiabatic film effectiveness data blowing ratio BR of 2.0 for hole spacings X/D = 6 and Y/D = 5, streamwise hole inclination angles of 20 deg and 30 deg, and contraction ratios Cr of 1 and 4, with line-averaging over y/D

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Fig. 22

Line-averaged adiabatic film effectiveness data blowing ratio BR of 10.0 for hole spacings X/D = 6 and Y/D = 5, streamwise hole inclination angles of 20 deg and 30 deg, and contraction ratios Cr of 1 and 4, with line-averaging over y/D

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Fig. 23

Variations of spatially averaged-adiabatic film effectiveness for blowing ratio BR of 2.0, hole spacings X/D = 6 and Y/D = 5, streamwise hole inclination angles of 20 deg and 30 deg, and contraction ratios Cr of 1 and 4

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Fig. 24

Variations of spatially averaged-adiabatic film effectiveness for blowing ratio BR of 5.0, hole spacings X/D = 6 and Y/D = 5, streamwise hole inclination angles of 20 deg and 30 deg, and contraction ratios Cr of 1 and 4

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Fig. 25

Variations of spatially averaged-adiabatic film effectiveness for blowing ratio BR of 10.0, hole spacings X/D = 6 and Y/D = 5, streamwise hole inclination angles of 20 deg and 30 deg, and contraction ratios Cr of 1 and 4

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Fig. 26

Variations of spatially averaged heat transfer coefficients for blowing ratio BR of 2.0, hole spacings X/D = 6 and Y/D = 5, streamwise hole inclination angles of 20 deg and 30 deg, and contraction ratios Cr of 1 and 4

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Fig. 27

Variations of spatially averaged heat transfer coefficients for blowing ratio BR of 5.0, hole spacings X/D = 6 and Y/D = 5, streamwise hole inclination angles of 20 deg and 30 deg, and contraction ratios Cr of 1 and 4

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Fig. 28

Variations of spatially averaged heat transfer coefficients for blowing ratio BR of 10.0, hole spacings X/D = 6 and Y/D = 5, streamwise hole inclination angles of 20 deg and 30 deg, and contraction ratios Cr of 1 and 4

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