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Research Papers: Forced Convection

Numerical Evaluation of Novel Shaped Holes for Enhancing Film Cooling Performance

[+] Author and Article Information
Xing Yang

Institute of Turbomachinery,
School of Energy and Power Engineering,
Xi'an Jiaotong University,
Xi'an, Shaanxi 710049, China
e-mail: yangxing90s@stu.xjtu.edu.cn

Zhao Liu

Institute of Turbomachinery,
School of Energy and Power Engineering,
Xi'an Jiaotong University,
Xi'an, Shaanxi 710049, China
e-mail: liuzhao@mail.xjtu.edu.cn

Zhenping Feng

Institute of Turbomachinery,
School of Energy and Power Engineering,
Xi'an Jiaotong University,
Xi'an, Shaanxi 710049, China
e-mail: zpfeng@mail.xjtu.edu.cn

1Corresponding author.

Contributed by the Heat Transfer Division of ASME for publication in the JOURNAL OF HEAT TRANSFER. Manuscript received July 10, 2014; final manuscript received January 28, 2015; published online March 24, 2015. Assoc. Editor: Jim A. Liburdy.

J. Heat Transfer 137(7), 071701 (Jul 01, 2015) (12 pages) Paper No: HT-14-1454; doi: 10.1115/1.4029817 History: Received July 10, 2014; Revised January 28, 2015; Online March 24, 2015

The overall film cooling performance of three novel film cooling holes has been numerically investigated in this paper, including adiabatic film cooling effectiveness, heat transfer coefficients as well as discharge coefficients. The novel holes were proposed to help cooling injection spread laterally on a cooled endwall surface. Three-dimensional Reynolds-averaged Navier–Stokes (RANS) equations with shear stress transport (SST) k-ω turbulence model were solved to perform the simulation based on turbulence model validation by using the relevant experimental data. Additionally, the grid independent test was also carried out. With a mainstream Mach number of 0.3, flow conditions applied in the simulation vary in a wide range of blowing ratio from 0.5 to 2.5. The coolant-to-mainstream density ratio (DR) is fixed at 1.75, which can be more approximate to real typical gas turbine applications. The numerical results for the cylindrical hole are in good agreement with the experimental data. It is found that the flow structures and temperature distributions downstream of the cooling injection are significantly changed by shaping the cooling hole exit. For a low blowing ratio of 0.5, the three novel shaped cooling holes present similar film cooling performances with the traditional cylindrical hole, while with the blowing ratio increasing, all the three novel cooling holes perform better, of which the bean-shaped hole is considered to be the best one in terms of the overall film cooling performance.

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References

Figures

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Fig. 2

Computation domain

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Fig. 3

Geometry of the novel shaped holes: (a) bean-shaped hole, (b) clover-shaped hole, and (c) wintersweet-shaped hole

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Fig. 1

Geometry of the experimental test case used in this study: (a) test section and (b) cylindrical hole [27]

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Fig. 6

Experimental and computational results of averaged film cooling effectiveness for cylindrical and shaped holes: (a) laterally averaged film cooling effectiveness and (b) spatially averaged film cooling effectiveness

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Fig. 4

Effect of turbulence models on laterally averaged film cooling effectiveness at M = 0.5

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Fig. 5

Grid independency test at M = 0.5: (a) velocity distribution in X-direction (x/D = 1, y/D = 0) and (b) laterally averaged film cooling effectiveness

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Fig. 10

Streamlines and velocity field within the holes (M = 2.0) for (a) cylindrical and (b) clover-shaped holes

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Fig. 11

Vorticity distribution on Y–Z plane and vortex core region by the interaction of coolant jet with crossflow (M = 2.5): (a) cylindrical, (b) bean-shaped, (c) clover-shaped, and (d) wintersweet-shaped

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Fig. 12

Two-dimension local distribution of heat transfer for cylindrical and shaped holes at various blowing ratios

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Fig. 13

Spatially averaged NHFR for cylindrical and shaped holes at various blowing ratios

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Fig. 7

Experimental and computational results for local film cooling effectiveness distribution for cylindrical and shaped holes at various blowing ratios

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Fig. 8

Spanwise local film cooling effectiveness distribution at M = 2.5: (a) x/D = 5, (b) x/D = 20, and (c) x/D = 40

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Fig. 9

Isosurface of V/Vm = 0.1 colored by normalized pressure at M = 1.0: (a) cylindrical, (b) bean-shaped, (c) clover-shaped, and (d) wintersweet-shaped

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Fig. 14

Discharge coefficient plotted versus pressure ratio

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Fig. 15

Pressure field over the hole exit cross section (z/D = 0.5) at pt,c/pm = 1.06: (a) cylindrical, (b) bean-shaped, (c) clover-shaped, and (d) wintersweet-shaped hole

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