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Research Papers: Gas Turbines: Turbomachinery

Unsteady Heat Transfer and Pressure Measurements on the Airfoils of a Rotating Transonic Turbine With Multiple Cooling Configurations

[+] Author and Article Information
Jeremy B. Nickol

The Ohio State University Gas
Turbine Laboratory,
2300 West Case Road,
Columbus, OH 43235

Randall M. Mathison

The Ohio State University Gas
Turbine Laboratory,
2300 West Case Road,
Columbus, OH 43235
e-mail: Mathison.4@osu.edu

Michael G. Dunn

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

Jong S. Liu, Malak F. Malak

Honeywell International,
Phoenix, AZ 85034

1Present address: Laboratory for Energy Conversion, ETH-Zurich, Zurich 8092, Switzerland.

Contributed by the Turbomachinery Committee of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received November 15, 2016; final manuscript received February 1, 2017; published online April 11, 2017. Editor: David Wisler.This research was partially funded by the Aviation Applied Technology Directorate under Agreement No. W911W6-08-2-0011. The U.S. Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation thereon. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of the Aviation Applied Technology Directorate or the U.S. Government.

J. Eng. Gas Turbines Power 139(9), 092601 (Apr 11, 2017) (10 pages) Paper No: GTP-16-1535; doi: 10.1115/1.4036059 History: Received November 15, 2016; Revised February 01, 2017

Measurements are presented for a high-pressure transonic turbine stage operating at design-corrected conditions with forward and aft purge flow and blade film cooling in a short-duration blowdown facility. Four different film-cooling configurations are investigated: simple cylindrical-shaped holes, diffusing fan-shaped holes, an advanced-shaped hole, and uncooled blades. A rainbow turbine approach is used so each of the four blade types comprises a wedge of the overall bladed disk and is investigated simultaneously at identical speed and vane exit conditions. Double-sided Kapton heat-flux gauges are installed at midspan on all three film-cooled blade types, and single-sided Pyrex heat-flux gauges are installed on the uncooled blades. Kulite pressure transducers are installed at midspan on cooled blades with round and fan-shaped cooling holes. Experimental results are presented both as time-averaged values and as time-accurate ensemble-averages. In addition, the results of a steady Reynolds-averaged Navier–Stokes computational fluid dynamics (RANS CFD) computation are compared to the time-averaged data. The computational and experimental results show that the cooled blades reduce heat transfer into the blade significantly from the uncooled case, but the overall differences in heat transfer among the three cooling configurations are small. This challenges previous conclusions for simplified geometries that show shaped cooling holes outperforming cylindrical holes by a great margin. It suggests that the more complicated flow physics associated with an airfoil operating in an engine-representative environment reduces the effectiveness of the shaped cooling holes. Time-accurate comparisons provide some insight into the complicated interactions that are driving these flows and make it difficult to characterize cooling benefits.

Copyright © 2017 by ASME
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References

Figures

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Fig. 1

Schematic of the OSU TTF

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Fig. 2

Schematic of the turbine stage with different flows

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Fig. 3

Photo of the rotor blade suction and pressure sides for a round-hole blade with static pressure instrumentation

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Fig. 4

Layout of multiple blade types in “rainbow rotor”

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Fig. 5

Photos of the three hole shapes: (a) cylindrical, (b) fan, and (c) advanced

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Fig. 6

Schematic of the three hole shapes

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Fig. 10

Airfoil Stanton number CFD (with 40–60% spanwise variation range) and midspan data for all three cooling hole shapes and uncooled CFD

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Fig. 9

Airfoil static pressure CFD (with 40–60% spanwise variation range) and midspan data

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Fig. 8

CFD heat-flux contour illustrating “boxing” method (not to scale) used to laterally average pressure and Stanton number for comparison

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Fig. 7

Full computational domain

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Fig. 11

Time-averaged data and CFD midspan Stanton number with spanwise variation for blade with (a) round holes, (b) fan-shaped holes, and (c) advanced-shaped holes

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Fig. 12

Ensemble-averages of Stanton number for heat-flux gauges at midspan of uncooled blades

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Fig. 13

Vane-passing offsets of maximum values of ensemble-averages

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Fig. 14

Effect of blade incidence angle on time-accurate heat-flux

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Fig. 15

Time-accurate heat-flux at 55% wetted-distance

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