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TECHNICAL PAPERS

A Numerical and Experimental Investigation of the Slot Film-Cooling Jet With Various Angles

[+] Author and Article Information
Rongguang Jia

Division of Heat Transfer, Lund Institute of Technology, Lund 22100, Sweden

Bengt Sundén1

Division of Heat Transfer, Lund Institute of Technology, Lund 22100, Swedenbengt.sunden@vok.lth.se

Petre Miron, Bruno Léger

LARA, Laboratoire Aquitain de Recherche en Aérothermique, Université de Pau, c/o Turbomeca, Boredes Cedex 64511, France

1

To whom correspondence should be addressed.

J. Turbomach 127(3), 635-645 (Jan 14, 2005) (11 pages) doi:10.1115/1.1929821 History: Received February 16, 2004; Revised January 14, 2005

Numerical simulations coupled with laser Doppler velocimetry (LDV) experiments were carried out to investigate a slot jet issued into a cross flow, which is relevant in the film cooling of gas turbine combustors. The film-cooling fluid injection from slots or holes into a cross flow produces highly complicated flow fields. In this paper, the time-averaged Navier-Stokes equations were solved on a collocated body-fitted grid system with the shear stress transport kω, V2F kϵ, and stress-ω turbulence models. The fluid flow and turbulent Reynolds stress fields were compared to the LDV experiments for three jet angles, namely, 30, 60, and 90 deg, and the jet blowing ratio is ranging from 2 to 9. Good agreement was obtained. Therefore, the present solution procedure was also adopted to calculations of 15 and 40 deg jets. In addition, the temperature fields were computed with a simple eddy diffusivity model to obtain the film-cooling effectiveness, which, in turn, was used for evaluation of the various jet cross-flow arrangements. The results show that a recirculation bubble downstream of the jet exists for jet angles larger than 40 deg, but it vanishes when the angle is <30deg, which is in good accordance with the experiments. The blowing ratio has a large effect on the size of the recirculation bubble and, consequently, on the film cooling effectiveness. In addition, the influence of boundary conditions for the jet and cross flow are also addressed in the paper.

Copyright © 2005 by American Society of Mechanical Engineers
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References

Figures

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Figure 1

The schematic view of (a) a mixing slot, (b) the computational domain and flow field, and (c) the grid. (There is an index skip in both x and y directions.)

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Figure 2

Experimental setup: (a) 1. laser cooling system and power supply; 2. laser source generator; 3. Bragg cell; 4. photomultiplicator; 5. transmitter-receiver optics head; 6. head moving 3D system; 7. Pentium II 350 MHz PC; 8. RSA 1=real-time signal analyzer (for green channel); 9. RSA 2=real-time signal analyzer (for blue channel); 10. fan-speed potentiometers; 11. electric fan air (for superior rectangular duct); 12. electric fan air (for inferior rectangular duct); 13. smoke generator; 14. differential pressure indicator; 15. hot-wire anemometer 16. aluminium slot model test plate; 17. exhaust outlet; and 18. optic fiber drive. (b) 3D view of the test section.

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Figure 3

The effect of the inlet boundary condition on: (a) velocity parallel to the wall at x∕B=1.0, (b) film cooling effectivness. (E–Uniform, F–Fully developed)

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Figure 4

Predicted distribution of the velocity parallel to the wall at x∕B=2, 4, 6, 8, and 10, in comparison to the experimental data of Chen and Hwang (9)

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Figure 5

The predicted distribution of the velocity fluctuation parallel to the wall at x∕B=2, 4, 6, 8, and 10, in comparison with the experimental data of Chen and Hwang (9)

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Figure 6

Predicted distribution of the normalized temperature (θ=(T−Tc)∕(Tj−Tc)) parallel to the wall at x∕B=2, 4, 6, 8, and 10, in comparison to the experimental data of Chen and Hwang (9)

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Figure 7

Streamline trace and distribution of the normalized Reynolds stress 10(u′∕Uc) for the 90-M2 case

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Figure 8

Distribution of the Reynolds stresses for the 90-M2 case: 10(v′∕Uc) and 10sign(u′v′¯)(∣u′v′∣¯0.5∕Uc)

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Figure 9

Mass conservation of the experiments at y∕B=−1: (a) the 90-M2 and (b) 60-M9 cases

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Figure 10

Streamline trace for the 60-M9 and 60-M4 cases

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Figure 11

Distribution of the velocity parallel to the wall at x∕B=1, 2, 3, 4, and 5

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Figure 12

Distribution of the velocity normal to the wall at x∕B=−1, 2, 3, 4, and 5

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Figure 13

Normalized distribution of the kinetic energy [(u′u′¯+v′v′¯)0.5∕Uc] at x∕B=1, 2, 3, 4, and 5

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Figure 14

Normalized distribution of the turbulent shear stress [10sign(u′v′¯)∣u′v′∣¯0.5∕Uc] at x∕B=1, 2, 3, 4, and 5

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Figure 15

Streamline traces and temperature distributions

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Figure 16

Film-cooling effectiveness for various injection angles, with M=2

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Figure 17

Film-cooling effectiveness for various blowing ratio, with α=30deg

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