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Research Papers

Heat Transfer for the Blade of a Cooled Stage and One-Half High-Pressure Turbine—Part II: Independent Influences of Vane Trailing Edge and Purge Cooling

[+] Author and Article Information
R. M. Mathison

Gas Turbine Laboratory, Ohio State University, 2300 West Case Road, Columbus, OH 43235mathison.4@osu.edu

C. W. Haldeman

Gas Turbine Laboratory, Ohio State University, 2300 West Case Road, Columbus, OH 43235haldeman.5@osu.edu

M. G. Dunn

Gas Turbine Laboratory, Ohio State University, 2300 West Case Road, Columbus, OH 43235dunn.129@osu.edu

J. Turbomach 134(3), 031015 (Jul 15, 2011) (11 pages) doi:10.1115/1.4003174 History: Received August 17, 2010; Revised August 23, 2010; Published July 15, 2011; Online July 15, 2011

The independent influences of vane trailing edge and purge cooling are studied in detail for a one-and-one-half stage transonic high-pressure turbine operating at design-corrected conditions. This paper builds on the conclusions of Part I, which investigated the combined influence of all cooling circuits. Heat-flux measurements for the airfoil, platform, tip, and root of the turbine blade, as well as the shroud and the vane side of the purge cavity, are used to track the influence of cooling flow. By independently varying the coolant flow rate through the vane trailing edge or purge circuit, the region of influence of each circuit can be isolated. Vane trailing edge cooling is found to create the largest reductions in blade heat transfer. However, much of the coolant accumulates on the blade suction surface and little influence is observed for the pressure surface. In contrast, the purge cooling is able to cause small reductions in heat transfer on both the suction and pressure surfaces of the airfoil. Its region of influence is limited to near the hub, but given that the purge coolant mass flow rate is 1/8 that of the vane trailing edge, it is impressive that any impact is observed at all. The cooling contributions of these two circuits account for nearly all of the cooling reductions observed for all three circuits in Part I, indicating that the vane inner cooling circuit that feeds most of the vane film-cooling holes has little impact on the downstream blade heat transfer. Time-accurate pressure measurements provide further insight into the complex interactions in the purge region that govern purge coolant injection. While the pressures supplying the purge coolant and the overall coolant flow rate remain fairly constant, the interactions of the vane pressure field and the rotor pressure field create moving regions of high pressure and low pressure at the exit of the cavity. This results in pulsing regions of injection and ingestion.

Copyright © 2012 by American Society of Mechanical Engineers
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References

Figures

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Figure 11

Influence of purge cooling flow rate on Stanton number for blade platform

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Figure 13

Influence of purge cooling on Stanton number for blade angel wing region

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Figure 14

Fluid and surface temperatures for angel wing region with purge flow variation

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Figure 12

Fluid temperature above blade platform for purge variation runs

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Figure 3

Pressure distribution for purge cavity exit

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Figure 4

Purge pressure time history for (a) high purge condition and (b) medium purge condition

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Figure 5

Ensemble averaged pressure for blade transducers near purge region for high purge condition

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Figure 6

FFT of pressure measurements near purge cavity

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Figure 7

Radial inlet temperature profiles for runs with purge flow variation

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Figure 8

Total temperature profile measured by blade leading edge thermocouples for purge variation runs

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Figure 9

Influence of purge cooling on pressure surface Stanton number distribution

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Figure 10

Influence of purge cooling on suction surface Stanton number distribution

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Figure 15

Influence of purge cooling flow rate on Stanton number for vane side of purge cavity

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Figure 16

Influence of purge cooling on Stanton number for outer shroud and blade tip

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Figure 17

Temperature profiles for runs investigating vane outer cooling

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Figure 18

Influence of vane outer circuit cooling on pressure surface Stanton number distribution

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Figure 19

Influence of vane outer circuit cooling on suction surface Stanton number distribution

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Figure 20

Influence of vane outer circuit cooling on Stanton number for blade platform

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Figure 21

Fluid temperature above blade platform for runs investigating vane outer cooling

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Figure 22

Influence of vane outer circuit cooling on Stanton number for blade angel wing region

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Figure 1

Schematic of instrumentation locations for vane and blade (not to scale)

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Figure 2

Pressure drop through purge cavity

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Figure 23

Influence of vane outer cooling circuit on Stanton number for outer shroud and blade tip

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