Turbulence structure resulting from interaction between an embedded vortex and wall jet.
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Authors
Green, James G.
Subjects
Embedded vortex
wall jet
turbulence
wall jet
turbulence
Advisors
Subramanian, Chelakara S.
Ligrani, Phillip M.
Date of Issue
1989
Date
June 1989
Publisher
Monterey, California. Naval Postgraduate School
Language
en_US
Abstract
Interactions of wall jets and vortices embedded in turbulent boundary layers commonly
occur near gas turbine blades and endwalls where film cooling is employed. These
interactions frequently result in undesirable heat transfer effects at blade and endwall
surfaces. In this research, a crossed hot-wire probe is used to measure the turbulence
structure resulting from this type of interaction.
The vortex is generated using a half-delta-wing vortex generator mounted at 12 degrees
with respect to a 10 m.'s mean velocity flow over a flat plate. A single injection
hole, .95 cm in diameter, inclined 30 degrees to the horizontal, is located under the
vortex downwash, 58 cm downstream from the vortex generator. Baseline measurements
were made at one streamwise location downstream of the injection hole for the cases: (1)
boundary layer only, (2) boundary layer with vortex, and (3) boundary layer with wall
jet. Measurement of the interaction between the boundary layer, vortex and 2.5 blowing
ratio wall jet was also made at this location. The 1.5 blowing ratio wall jet interaction
was measured at three additional streamwise locations.
Reynolds stress tensor components, vorticity distributions and mean velocities show
that the vortex significantlv alters the turbulence structure of the 1.5 blowing ratio wall
jet at all lour streamwise locations. Here the injectant is swept away from the injection
hole by the vortex rotation. The most significant alterations to the turbulence structure
occur in the vortex upwash region and beneath the vortex core. The 2.5 blowing ratio
jet is much more resistant to disturbance by the vortex.
Type
Thesis
Description
Series/Report No
Department
Mechanical Engineering
Organization
Identifiers
NPS Report Number
Sponsors
Funder
Format
213 p.
Citation
Distribution Statement
Approved for public release; distribution is unlimited.
Rights
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.