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Research Papers

# Influence of Scaling Parameters and Gas Properties on Overall Effectiveness on a Leading Edge Showerhead

[+] Author and Article Information
Connor J. Wiese, Carol E. Bryant

Air Force Research Laboratory,
Wright-Patterson Air Force Base,
OH 45433

James L. Rutledge

Air Force Institute of Technology,
Wright-Patterson Air Force Base,
OH 45433
e-mail: james.rutledge@us.af.mil

Marc D. Polanka

Air Force Institute of Technology,
Wright-Patterson Air Force Base,
OH 45433

1Corresponding author.

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received August 15, 2018; final manuscript received August 22, 2018; published online October 24, 2018. Editor: Kenneth Hall.This material is declared a work of the U.S. Government and is not subject to copyright protection in the United States. Approved for public release; distribution is unlimited.

J. Turbomach 140(11), 111007 (Oct 24, 2018) (12 pages) Paper No: TURBO-18-1204; doi: 10.1115/1.4041292 History: Received August 15, 2018; Revised August 22, 2018

## Abstract

Testing new turbine cooling schemes at engine conditions becomes cost prohibitive as gas-path temperatures increase. As a result, turbine components are simulated in a laboratory with a large-scale model that is sized and constructed out of a selected material so that the Biot number is matched between the laboratory and engine conditions. Furthermore, the experimental temperatures are lower, so the surface temperature that the metal component would experience is scaled via the overall cooling effectiveness, $ϕ$. Properly measuring $ϕ$ requires that the relevant flow physics must be matched, thus the Reynolds numbers is matched—both those of the freestream and the coolant, as well as the other scaling parameters, such as the mass flux, momentum flux, and velocity ratios. However, if the coolant-to-freestream density ratio does not match that of the engine condition, the mass flux, momentum flux, coolant and freestream Reynolds numbers, and coolant-to-freestream velocity ratios cannot be matched simultaneously to the engine condition. Furthermore, the coolant thermal transfer properties are unaccounted for in these parameters, despite their large influence on the resultant overall effectiveness. While much research has focused on the effects of the coolant-to-freestream density ratio, this study examines the influence of other thermodynamic properties, in particular the specific heat, which differ substantially between experimental and engine conditions. This study demonstrates the influence of various coolant properties on the overall effectiveness distribution on a leading edge by selectively matching $M$, $I$, and $ACR$ with air, argon, and carbon dioxide coolants.

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## References

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## Figures

Fig. 1

Model schematic with top-down (a), β-plane (b), and stagnation (c) views

Fig. 2

Representative view of the ten active cooling holes (white ellipses), the region of interest (shaded rectangle), and the stagnation line (dashed line)

Fig. 3

Test section schematic showing relative model and instrumentation locations

Fig. 4

Effect of increasing model kwall from kwall = 1.009 W/m K (left) to kwall = 3.5 W/m K (right)

Fig. 5

Sensitivity of ϕ to Bi for various values of η, χ = 0.9 and hf/hi = 3

Fig. 6

Row blowing ratio, Mrow, as a function of target blowing ratio, M, and β angle

Fig. 7

Infrared camera calibration curve

Fig. 8

ϕ contours for air at M = 1.0, 1.5, and 2.0

Fig. 9

ϕ (left) and Δϕ (right) contours for carbon dioxide at M = 1.0, 1.5, and 2.0

Fig. 10

ϕ (left) and Δϕ (right) contours for argon at M = 1.0, 1.5, and 2.0

Fig. 11

ϕ contours for air at I = 1.0, 1.5, and 2.0

Fig. 12

ϕ (left) and Δϕ (right) contours for carbon dioxide at I = 1.0, 1.5, and 2.0

Fig. 13

ϕ (left) and Δϕ (right) contours for argon at I = 1.0, 1.5, and 2.0

Fig. 14

Stagnation region detail of ϕ at I = 1.0, 1.5, and 2.0 for air (left), CO2 (center), and Ar (right)

Fig. 15

ϕ (left) and Δϕ (right) contours for carbon dioxide at ACR = 1.0, 1.5, and 2.0

Fig. 16

ϕ (left) and Δϕ (right) contours for argon at ACR= 1.0

## Errata

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