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Research Papers

Computational Study of a Midpassage Gap and Upstream Slot on Vane Endwall Film-Cooling

[+] Author and Article Information
Satoshi Hada

Department of Gas Turbine Engineering, Mitsubishi Heavy Industries, Ltd., Takasago, Hyogo, 676-8686, Japan

Karen A. Thole

Department of Mechanical and Nuclear Engineering, Pennsylvania State University, University Park, PA 16802

J. Turbomach 133(1), 011024 (Sep 24, 2010) (9 pages) doi:10.1115/1.4001135 History: Received September 21, 2008; Revised December 14, 2009; Published September 24, 2010; Online September 24, 2010

Turbines are designed to operate with high inlet temperatures to improve engine performance. To reduce NOx resulting from combustion, designs for combustors attempt to achieve flat pattern factors that results in high levels of heat transfer to the endwall of the first stage vane. Film-cooling is still one of the most effective cooling methods for many component features including the endwall. This paper presents results from a computational study of a film-cooled endwall. The endwall design considers both an upstream slot, representing the combustor—turbine junction, and a midpassage slot, representing the mating between the adjacent vanes. The focus of this study is on comparing adiabatic effectiveness levels on the endwall with varying leakage flowrates and gap widths. Results indicate reasonable agreement between computational predictions and experimental measurements of adiabatic effectiveness levels along the endwall. The results of this study show that the midpassage slot has a large influence on the coolant coverage. It was also shown that by raising the combustor relative to the downstream vane endwall, better coolant coverage from the combustor-turbine slot could be achieved.

Copyright © 2011 by American Society of Mechanical Engineers
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References

Figures

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Figure 1

Directions of the coolant hole injection, the upstream slot location, the midpassage gap location and investigated planes for secondary flow analysis

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Figure 2

Cross section view of the midpassage gap plenum and accompanying seal strip (see Table 1)

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Figure 3

Endwall configurations showing the four alignment modes for two adjacent vane platforms: (a) case where all surfaces are flush, (b) cascade case (the suction surface is lower than pressure and combustor surfaces), (c) cascade case (the suction surface is lower than the pressure surface but at the same length height as the combustor surface), (d) combustor surface is higher than the suction and pressure surfaces, and (e) dam case (suction surface is higher than pressure and combustor surfaces)

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Figure 4

Computational mesh including the coolant cavity, the upstream contraction area, and the exit area

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Figure 5

Contours of adiabatic effectiveness on the endwall for experimental results (a) and (b) without midpassage gap (19) and for computational results (c) with (d) without midpassage gap

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Figure 6

Computational and experimental pitch-averaged effectiveness with and without midpassage gap

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Figure 7

Computational results of the adiabatic effectiveness along the streamtrace (0.5P) shown in Fig. 1 without and with midpassage gap flowing at 0.0125% (case 2)

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Figure 8

The exiting velocity distribution along the midpassage gap for an aligned endwall (case 2)

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Figure 9

Secondary flow vector and non dimensional thermal field for the secondary flow plane (x/L=40%) for (a) no midpassage gap and (b) with midpassage gap

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Figure 10

Secondary flow vector and nondimensional thermal field for the secondary flow plane (x/L=60%) for (a) no midpassage gap and (b) with a midpassage gap

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Figure 11

Contours of adiabatic effectiveness on the endwall for computational results for (a) 0.0125% midpassage gap flow, (b) 0.3% midpassage gap flow, (c) 0.3% midpassage gap flow with 0.33 seal strip gap, and (d) 0.3% midpassage gap flow with 0.11 seal gap

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Figure 12

Nondimensional velocity distribution at the exit of the midpassage gap for cases 2–5

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Figure 13

Nondimensional temperature comparison along midpassage gap for cases 2–5

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Figure 14

Velocity contour and nondimensional thermal field in the midpassage gap for (a) 0.0125% midpassage gap flow with original seal strip gap (case 2) and (b) 0.3% with 0.11 seal strip gap (case 5)

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Figure 15

Contours of adiabatic effectiveness on the endwall for (a) case 6—cascade with suction side down (Fig. 3), (b) case 7—cascade with pressure side up (Fig. 3), (c) case 8—cascade with combustor-up and midpassage flush (Fig. 3), and (d) case 9—dam with suction side up (Fig. 3, note that U̱ refers to raised side and Ḏ refers to lowered side)

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Figure 16

(a) Suction side and (b) pressure side pitchwise average of the adiabatic effectiveness for flush and four misalignment cases

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