Full-Coverage Effusion Cooling in External Forced Convection: Sparse and Dense Hole Arrays

Living reference work entry

Abstract

To illustrate forced convection, external flow effects and phenomena, considered are full coverage effusion cooling arrangements. Parameters and phenomena considered include: (1) blowing ratio BR, (2) magnitude of main flow streamwise static pressure gradient (quantified by mainstream passage contraction ratio Cr values of 1, 3, 4, and 5), (3) streamwise development (quantified by variations with x/D), (4) effusion cooling hole inclination angle α, and (5) effusion hole spacing, ranging from dense to sparse (characterized by X/D values of 6 and 18, and Y/D values of 3, 5, and 7). As such, the film cooling holes in adjacent streamwise rows are staggered with respect to each other, with sharp edges, and streamwise inclination angles of either 20 degrees or 30 degrees, with respect to the liner surface. Data are provided for turbulent film cooling, blowing ratios (at the test section entrance) of 2.0, 5.0, and 10.0, coolant Reynolds numbers of 12,000 for BR = 5.0, freestream temperatures from 75 °C to 115 °C, a film hole diameter of 7 mm, and density ratios from 1.15 to 1.25. Data include local, line-averaged, and spatially-averaged adiabatic film effectiveness data and local, line-averaged, and spatially-averaged heat transfer coefficient data. Varying blowing ratio values are utilized along the length of the contraction passage, which contains the cooling hole arrangement, when contraction ratio is different from 1. Dependence on blowing ratio indicates important influences of coolant concentration and distribution. For example, line-averaged and spatially-averaged adiabatic effectiveness data show vastly different changes with blowing ratio BR for the configurations with contraction ratios of 1 and 4. These changes from acceleration are thus mostly due to different blowing ratio distributions along the test section.

Nomenclature

BR

Film cooling blowing ratio

Cr

Contraction ratio, ratio of inlet to exit flow areas

D

Film cooling hole diameter

hc

Local iso-energetic heat transfer coefficient

\( \overline{hc} \)

Line-averaged iso-energetic heat transfer coefficient

\( \overline{\overline{hc}} \)

Spatially-averaged iso-energetic heat transfer coefficient

K

Acceleration parameter

\( {\dot{m}}_c \)

Cumulative coolant mass flow rate

\( {\dot{m}}_{\infty } \)

Local freestream mass flow rate

Refc

Film cooling Reynolds number

T

Temperature

Tw

Local wall temperature

Taw

Local adiabatic wall temperature

Tc

Spatially-averaged coolant static temperature

T

Local freestream static temperature

Tu

Turbulence intensity

ufc

Local coolant exit velocity

u

Local freestream velocity

x

Streamwise coordinate

X

Streamwise film hole spacing

y

Spanwise coordinate

Y

Spanwise film hole spacing

z

Surface normal coordinate

Greek Symbols

α

Streamwise hole inclination angle

ρc

Coolant density

ρ

Freestream density

ν

Kinematic viscosity

η

Local adiabatic film cooling effectiveness

\( \overline{\eta} \)

Line-averaged adiabatic film cooling effectiveness

\( \overline{\overline{\eta}} \)

Spatially-averaged adiabatic film cooling effectiveness

Notes

Acknowledgments

The present chapter presents results of research efforts that were sponsored by Solar Turbines Inc. The author gratefully acknowledges this support, as well as the opportunity to work and interact within an excellent engineering team.

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Copyright information

© Springer International Publishing AG 2017

Authors and Affiliations

  1. 1.Propulsion Research Center, Department of Mechanical and Aerospace EngineeringUniversity of Alabama in HuntsvilleHuntsvilleUSA

Section editors and affiliations

  • Sumanta Acharya
    • 1
  1. 1.Herff College of Engineering,Department of Mechanical EngineeringThe University of MemphisMemphisUSA

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