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Research Papers

Single and Multiple Row Endwall Film-Cooling of a Highly Loaded First Turbine Vane With Variation of Loading

[+] Author and Article Information
Martin Kunze

Technische Universität Dresden,
Institute of Fluid Mechanics,
Dresden, D-01062Germany
e-mail: martin.kunze@tu-dresden.de

Konrad Vogeler

Technische Universität Dresden,
Institute of Fluid Mechanics,
Dresden, D-01062Germany
e-mail: konrad.vogeler@tu-dresden.de

Michael Crawford

Siemens Energy, Inc.,
4400 Alafaya Trail,
Orlando, FL 32826-2399
e-mail: michael.crawford@siemens.com

Glenn Brown

Siemens Energy, Inc.,
1680 South Central Boulevard,
Jupiter, FL 33458
e-mail: glenn.brown@siemens.com

1Corresponding author.

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received March 25, 2013; final manuscript received August 26, 2013; published online November 28, 2013. Assoc. Editor: Kenichiro Takeishi.

J. Turbomach 136(6), 061012 (Nov 28, 2013) (14 pages) Paper No: TURBO-13-1045; doi: 10.1115/1.4025688 History: Received March 25, 2013; Revised August 26, 2013

This paper reports endwall film-cooling investigations with single and multiple rows of fan-shaped film holes using temperature-sensitive paint (TSP). The experiments are carried out in a six-bladed linear cascade based on the geometry of a highly loaded gas turbine first vane. The film effectiveness performance of the cooling rows is investigated under the influence of enhanced near-wall secondary flow. Tests are conducted at three different loading conditions changing the profile incidence. Film-cooling injection is established at elevated coolant density ratios of 1.4 using heated carbon dioxide. Due to the finite thermal conductivity of the wall material, the heat conduction effects observed in the measured temperature fields are assessed by a newly developed data analysis based on a finite element thermal analysis and tracking algorithms along CFD-computed near-wall surface streamlines. The results showed that the coolant trajectories are visibly influenced revealing the intense interaction between the film jets and the near-wall flow field. These effects are certainly enhanced with higher incidence leading to increased streamwise coolant consumption and reduced wall coverage. At the cascade inlet, the film-cooling injection is significantly affected by the near-wall flow field showing distinct over- and undercooled regions. Due to the enhanced deflection and mixing of the film jets injected from a single row, area-averaged film effectiveness and wall coverage decreases about 9 and 11%, respectively. With adding more cooling holes to this endwall area, the influence of the enhanced secondary flow becomes more pronounced. Hence, larger reduction in film effectiveness of 23% and wall coverage with 28% is observed. For single row injection at the airfoil pressure side, the stronger secondary flow motion with intensified streamwise mixing leads to a visibly decreased endwall coverage ratio of about 38% and maximum flow path reduction of about 41%. In this case, film effectiveness is found to be reduced up to 47% due to the small amount of coolant injected through this row. This effect is significantly smaller when more cooling rows are added showing an almost constant cooling performance for all incidence cases.

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Figures

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Fig. 4

Analysis of temperature fields along near-wall surface streamlines (a), comparison of CFD-near wall streamlines to oil-film visualization (b), and measured temperature fields with coolant injection (c)

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Fig. 3

Schematic of data analysis procedure for TSP-images (a) and FE-based conduction correction (b)

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Fig. 2

Schematic of endwall cooling scheme with diffuser hole geometry

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Fig. 1

Schematic of cascade wind tunnel with test section setup

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Fig. 5

Masking method to evaluate area-averaged film effectiveness and endwall area fraction (dark-gray region visualize masked section)

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Fig. 6

Endwall pressure field with variation of inlet flow angle (a): β1,ms = 94.8 deg, (b): β1,ms = 75.0 deg, and (c) β1,ms = 49.4 deg

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Fig. 7

Normalized adiabatic film effectiveness ηaw/ηref (left) and streamwise film effectiveness ηSL/ηref (right) for film row SS-1 with variation of loading (a)–(c) for M¯=1.55, DR=1.40

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Fig. 11

Normalized adiabatic film effectiveness for CO2 -injection for two row groups with variation of loading: SS-1 to PS-3, m·c/m·m = 0.0015, M¯ = 1.59, DR = 1.41 (a)–(c) and PS-4 to PS-8, m·c/m·m = 0.0007, M¯ = 1.61, DR = 1.41 (d)–(f). (a): SS1-PS3, β1,ms = 94.8 deg, (b): β1,ms = 75.0 deg, (c): β1,ms = 49.4 deg, (d): PS4-PS8, β1,ms = 94.8 deg, (e): β1,ms = 75.0 deg, (f): β1,ms = 49.4 deg.

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Fig. 12

Area-averaged film effectiveness ηgl/ηref (left) and cooled endwall area ratio Aew/Aew,op (right) for multiple row injection with variation of loading; (a): film injection through rows SS-1 to PS-3, (b): film injection through rows PS-4 to PS-8

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Fig. 8

Area-averaged film effectiveness ηgl/ηref (left) and cooled endwall area ratio Aew/Aew,op (right) for film row SS-1 with variation of loading

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Fig. 9

Normalized adiabatic film effectiveness ηaw/ηref (left) and streamwise film effectiveness ηSL/ηref (right) for film hole row PS-7 and PS-8 with variation of loading (a)–(c) for M¯=1.55, DR = 1.40

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Fig. 10

Area-averaged film effectiveness ηgl/ηref (left) and cooled endwall area ratio Aew/Aew,op (right) for film hole row PS-7 and PS-8 with variation of loading

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