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Research Papers

# Turbine Airfoil Net Heat Flux Reduction With Cylindrical Holes Embedded in a Transverse Trench

[+] Author and Article Information
Katharine L. Harrison, John R. Dorrington, Jason E. Dees, David G. Bogard

Mechanical Engineering Department, University of Texas at Austin, Austin, TX 78712

Ronald S. Bunker

GE Global Research Center, Niskayuna, NY 12309

J. Turbomach 131(1), 011012 (Oct 17, 2008) (8 pages) doi:10.1115/1.2812967 History: Received July 02, 2007; Revised August 15, 2007; Published October 17, 2008

## Abstract

Film cooling adiabatic effectiveness and heat transfer coefficients for cylindrical holes embedded in a $1d$ transverse trench on the suction side of a simulated turbine vane were investigated to determine the net heat flux reduction. For reference, measurements were also conducted with standard inclined, cylindrical holes. Heat transfer coefficients were determined with and without upstream heating to isolate the hydrodynamic effects of the trench and to investigate the effects of the thermal approach boundary layer. Also, the effects of a tripped versus an untripped boundary layer were explored. For both the cylindrical holes and the trench, heat transfer augmentation was much greater for the untripped approach flow. A further increase in heat transfer augmentation was caused by use of upstream heating, with as much as a 180% augmentation for the trench. The tripped approach flow led to much lower heat transfer augmentation than the untipped case. The net heat flux reduction for the trench was found to be significantly higher than for the row of cylindrical holes.

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## Figures

Figure 1

Schematic of test section

Figure 2

Detailed representation of the test vane

Figure 3

Narrow trench configuration

Figure 4

Location of trip and heat flux plates

Figure 5

Boundary layer profiles for tripped and untripped heat transfer experiments

Figure 6

Distributions of η¯ for the base line and trench without a trip

Figure 7

Surface contours of η without upstream heating and without a trip for the base line (top) and trench (bottom)

Figure 8

Surface contours of hf∕h0¯ without upstream heating and without a trip for the base line (top) and the trench (bottom)

Figure 9

Reference smooth surface h0¯ values for four operating conditions

Figure 10

Base line hf∕h0¯ with and without upstream heating and without a trip

Figure 11

Base line hf∕h0¯ with and without upstream heating and with a trip

Figure 12

Trench hf∕h0¯ with and without upstream heating and without a trip

Figure 13

Trench hf∕h0¯ with and without upstream heating and with a trip

Figure 14

Distributions of h¯f with an exposed trench but with no blowing (M=0)

Figure 15

Comparison of hf∕h0¯ for the trench and base line at M=1

Figure 16

Base line Δqr¯ with and without upstream heating and without a trip

Figure 17

Trench Δqr¯ with and without upstream heating and without a trip

Figure 18

Comparison of base line and trench Δqr¯ with upstream heating and without a trip

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