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Research Papers

Effect of Coolant Density on Leading Edge Showerhead Film Cooling Using the Pressure Sensitive Paint Measurement Technique

[+] Author and Article Information
Je-Chin Han

e-mail: jc-han@tamu.edu
Turbine Heat Transfer Laboratory,
Department of Mechanical Engineering,
Texas A&M University,
College Station, TX 77843-3123

1Corresponding author.

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received July 9, 2013; final manuscript received July 18, 2013; published online September 27, 2013. Editor: Ronald Bunker.

J. Turbomach 136(5), 051011 (Sep 27, 2013) (10 pages) Paper No: TURBO-13-1145; doi: 10.1115/1.4025225 History: Received July 09, 2013; Revised July 18, 2013

The density ratio effect on leading edge showerhead film cooling has been studied experimentally using the pressure sensitive paint (PSP) mass transfer analogy method. The leading edge model is a blunt body with a semicylinder and an after body. There are two designs: seven-row and three-row of film cooling holes for simulating a vane and blade, respectively. The film holes are located at 0 (stagnation row), ±15, ±30, and ±45 deg for the seven-row design, and at 0 and ±30 for the three-row design. Four film hole configurations are used for both test designs: radial angle cylindrical holes, compound angle cylindrical holes, radial angle shaped holes, and compound angle shaped holes. The coolant to mainstream density ratio varies from DR = 1.0, 1.5, to 2.0 while the blowing ratio varies from M = 0.5 to 2.1. Experiments were conducted in a low speed wind tunnel with Reynolds number 100,900 based on mainstream velocity and diameter of the cylinder. The mainstream turbulence intensity near the leading edge model is about 7%. The results show the shaped holes have an overall higher film cooling effectiveness than the cylindrical holes, and the radial angle holes are better than the compound angle holes, particularly at a higher blowing ratio. A larger density ratio makes more coolant attach to the surface and increases film protection for all cases. Radial angle shaped holes provide the best film cooling at a higher density ratio and blowing ratio for both designs.

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References

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Figures

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Fig. 1

Leading edge film cooling test facility

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Fig. 2

Semicylinder test section and an after body

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Fig. 3

Seven-row design: (a) radial angle cylindrical holes, (b) compound angle cylindrical holes, (c) radial angle shaped holes, and (d) compound angle shaped holes

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Fig. 4

Three-row design: (a) radial angle cylindrical holes, (b) compound angle cylindrical holes, (c) radial angle shaped holes, and (d) compound angle shaped holes

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Fig. 5

Definition of orientations and hole shape: (a) cylindrical hole and (b) shaped hole

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Fig. 6

(a) Principle of measurement using PSP. (b) Calibration curve for PSP at three different temperatures.

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Fig. 7

Schematic of local coolant mass flow rate distributions and local blowing ratio: seven-row design (left) and three-row design (right)

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Fig. 8

Film cooling effectiveness contour plot of seven-row design: radial angle cylindrical holes

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Fig. 9

Film cooling effectiveness contour plot of seven-row design for all film hole configuration with DR = 1.5

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Fig. 10

Film cooling effectiveness contour plot of three-row design: radial angle shaped holes

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Fig. 11

Effect of blowing ratio on spanwise averaged film cooling effectiveness of seven-row design for all configurations with DR = 1.5

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Fig. 12

Effect of blowing ratio on spanwise averaged film cooling effectiveness of three-row design for all configurations with DR = 2.0

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Fig. 13

Effect of hole configuration on spanwise averaged film cooling effectiveness with a medium blowing ratio (left: seven-row design with M = 1.2; right: three-row design with M = 1.0)

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Fig. 14

Effect of density ratio on spanwise averaged film cooling effectiveness of three-row design for two configurations

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Fig. 15

Area averaged film cooling effectiveness of seven-row design (upper) and three-row design (lower)

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Fig. 16

Effect of momentum flux ratio on film cooling effectiveness for three-row design

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