The effects of an embedded vortex on a film cooled turbulent boundary layer.

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Author
Joseph, Stephen Leo
Date
1986-12Advisor
Ligrani, P.M.
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Show full item recordAbstract
This study was designed to model some of the secondary flow effects
on endwalls, blades, and combustion chambers of gas turbine engines.
Measurements were made in a turbulent boundary layer developing over a
flat plate, using a single row of injection holes spaced three diameters
apart inclined at 30 degrees with respect to horizontal. The hole diameter
to boundary layer thickness ratio, non-dimensional injection temperatures,
and blowing rates were the same as exist in turbine first
stages. The injection system was designed to provide uniform injection
temperatures for various blowing rates with discharge coefficients
ranging from 0.58 to 0.73. The heat transfer surface was designed to
provide constant heat flux with adjustable temperature range.
Experimental heat transfer results were obtained with a turbulent
boundary layer only, with boundary layer and injection of film cooling, with boundary layer and embedded vortex, and finally with
boundary layer, film cooling, and embedded vortex. Results
with a turbulent boundary layer only show excellent agreement
with correlations accounting for unheated starting length.
Results with film cooling only show expected trends, and results
with embedded vortex only show excellent agreement with data
from the literature. The effects of the vortex on heat transfer
in the film cooled boundary layer are significant and important:
(]) On the downwash side of the vortex, heat transfer is
augmented, effects of the film cooling are negated and local
"hot-spots" will exist in engines. (2) Near the upwash side of
the vortex coolant is pushed to the side of the vortex,
appearing to augment the protection provided by film cooling.
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This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.Collections
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