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TECHNOLOGY REVIEW

Gas Turbine Heat Transfer: Ten Remaining Hot Gas Path Challenges

[+] Author and Article Information
Ronald S. Bunker

 GE Global Research Center, Niskayuna, NY 12309

J. Turbomach 129(2), 193-201 (Jul 16, 2006) (9 pages) doi:10.1115/1.2464142 History: Received July 12, 2006; Revised July 16, 2006

The advancement of turbine cooling has allowed engine design to exceed normal material temperature limits, but it has introduced complexities that have accentuated the thermal issues greatly. Cooled component design has consistently trended in the direction of higher heat loads, higher through-wall thermal gradients, and higher in-plane thermal gradients. The present discussion seeks to identify ten major thermal issues, or opportunities, that remain for the turbine hot gas path (HGP) today. These thermal challenges are commonly known in their broadest forms, but some tend to be little discussed in a direct manner relevant to gas turbines. These include uniformity of internal cooling, ultimate film cooling, microcooling, reduced incident heat flux, secondary flows as prime cooling, contoured gas paths, thermal stress reduction, controlled cooling, low emission combustor-turbine systems, and regenerative cooling. Evolutionary or revolutionary advancements concerning these issues will ultimately be required in realizable engineering forms for gas turbines to breakthrough to new levels of performance. Herein lies the challenge to researchers and designers. It is the intention of this summary to provide a concise review of these issues, and some of the recent solution directions, as an initial guide and stimulation to further research.

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Copyright © 2007 by American Society of Mechanical Engineers
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References

Figures

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Figure 1

Generic cooling technology curves and example cooled hpt blade

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Figure 2

Example of internal airfoil wall network cooling

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Figure 3

Alternate film hole shaping for greater effectiveness

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Figure 4

Schematic of microcooled airfoil

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Figure 5

Example of roughened turbine airfoil

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Figure 6

Schematic of secondary purge and leakage flows

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Figure 7

Turbine blade end-wall contour example

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Figure 8

Shell and spar airfoil design

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Figure 9

Controlled film cooling (hypothesized)

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Figure 10

Trapped vortex combustor

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Figure 11

One version of regenerative cooling for a turbine cycle

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Figure 12

Technology impact-risk ranking of the challenges

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