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Research Papers

The Effect of the Combustor-Turbine Slot and Midpassage Gap on Vane Endwall Heat Transfer

[+] Author and Article Information
Stephen P. Lynch, Karen A. Thole

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

J. Turbomach 133(4), 041002 (Apr 19, 2011) (9 pages) doi:10.1115/1.4002950 History: Received May 19, 2010; Revised June 04, 2010; Published April 19, 2011; Online April 19, 2011

Turbine vanes are generally manufactured as single- or double-airfoil sections that are assembled into a full turbine disk. The gaps between the individual sections, as well as a gap between the turbine disk and the combustor upstream, provide leakage paths for relatively higher-pressure coolant flows. This leakage is intended to prevent ingestion of the hot combustion flow in the primary gas path. At the vane endwall, this leakage flow can interfere with the complex vortical flow present there and thus affect the heat transfer to that surface. To determine the effect of leakage flow through the gaps, heat transfer coefficients were measured along a first-stage vane endwall and inside the midpassage gap for a large-scale cascade with a simulated combustor-turbine interface slot and a midpassage gap. For increasing combustor-turbine leakage flows, endwall surface heat transfer coefficients showed a slight increase in heat transfer. The presence of the midpassage gap, however, resulted in high heat transfer near the passage throat where flow is ejected from that gap. Computational simulations indicated that a small vortex created at the gap flow ejection location contributed to the high heat transfer. The measured differences in heat transfer for the various midpassage gap flowrates tested did not appear to have a significant effect.

Copyright © 2011 by American Society of Mechanical Engineers
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References

Figures

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Figure 2

(a) The vane test section with simulated upstream slot and midpassage gap leakage interfaces, (b) section view of upstream slot, and (c) section view of midpassage gap with seal strip; see Table 2 for dimensions

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Figure 3

(a) The computational domain with boundaries and (b) view of the endwall and suction-side airfoil mesh

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Figure 4

Comparison of endwall heat transfer with no upstream slot for (a) no gap (2) and (b) this study with 0% MFR from the midpassage gap

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Figure 5

Endwall heat transfer with an upstream slot blowing at 1.0% MFR for a slot at (a) X/Cax=−0.77(2) versus at (b) X/Cax=−0.3

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Figure 6

Nondimensional leakage velocity from the upstream slot for varying slot flowrates and locations upstream of the vane

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Figure 8

Endwall heat transfer for 0.75% slot MFR and 0% gap MFR from (a) experimental results and from predictions using the (b) RNG k-ε and (c) k-ω SST turbulence models in FLUENT (18)

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Figure 9

Streamlines released from (a) the upstream slot plenum inlet and (b) from 1% span at X/Cax=−0.51 upstream of the vane

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Figure 10

Endwall heat transfer for 0% MFR from the midpassage gap and upstream slot flowrates of (a) 0.75% MFR, (b) 0.85% MFR, and (c) 1.0% MFR

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Figure 11

Pitchwise-averaged endwall St values on the suction-side platform for 0% MFR from the midpassage gap and varying upstream slot flowrates

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Figure 12

Endwall heat transfer for 0.75% MFR from the upstream slot and midpassage gap flowrates of (a) 0% MFR, (b) 0.3% MFR, and (c) 0.5% MFR

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Figure 13

Pitchwise-averaged endwall heat transfer on the suction-side platform for varying midpassage gap flowrates

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Figure 14

Heat transfer on the inner channel walls of the midpassage gap for 0.75% upstream slot MFR and varying midpassage gap flowrates

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Figure 1

Depiction of the large-scale wind tunnel with corner test section

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Figure 7

A comparison of pitchwise-averaged heat transfer for the suction side and pressure side of the endwall around the midpassage gap

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Figure 15

Comparison of endwall heat transfer for slot MFRs of (a) 0.75% and (b) 1.0% to adiabatic film effectiveness (12) at slot MFRs of (c) 0.75% and (d) 1.0%

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