2026-09-19T09:24:38Zhttps://dspace.mit.edu/server/oai/requestoai:dspace.mit.edu:1721.1/986852022-01-13T07:53:53Zcom_1721.1_7582com_1721.1_7581col_1721.1_131023
Edward M. Greitzer and Choon S. Tan.
Jedamski, Devon (Devon James)
Massachusetts Institute of Technology. Department of Aeronautics and Astronautics.
Massachusetts Institute of Technology. Department of Aeronautics and Astronautics
2015-09-17T19:04:46Z
2015-09-17T19:04:46Z
2015
2015
http://hdl.handle.net/1721.1/98685
920686308
Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2015.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 87-88).
The effect of axial turbine stage inlet non-uniformities are examined through two model problems: wake attenuation and hot streak processing. In the first, twodimensional calculations (RANS and URANS) are used to identify the mechanisms contributing to upstream stator wake attenuation through a turbine blade row. For a representative turbine rotor, pitch and time-averaged wake attenuation by 74% percent is demonstrated at one quarter chord downstream of the trailing edge. Near the pressure surface, the wake stagnation pressure increases by up to 42% above the freestream stagnation pressure. The mechanisms identified are a localized reduction in flow-through time for wake fluid near the pressure surface, compared to the freestream, and an unsteady pressure field (Op/&t) in the rotor reference frame that increases work extraction in the freestream relative to wake fluid. For the second model problem, three-dimensional calculations (RANS and URANS) identify a difference in turbine efficiency sensitivity to thermal distortion between a geometry with no tip gap and a geometry with a finite tip gap. The turbine with a tip clearance is 2.5 times less sensitive, in terms of efficiency decrease, to an inlet hot streak. For the tip gap and no tip gap geometries, the efficiency drops by 0.75% and 1.86% respectively for a peak temperature non-uniformity equal to 0.6 times the combustor temperature rise. The difference in efficiency decrease, due to hot streak, between the two geometries is linked to a reduction in tip leakage mixing losses caused by changes in relative rotor inlet flow angle with and without hot streak.
by Devon Jedamski.
S.M.
88 pages
eng
Massachusetts Institute of Technology
M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.
http://dspace.mit.edu/handle/1721.1/7582
Aeronautics and Astronautics.
Turbine inlet non-uniformities and unsteady mechanisms
Thesis
application/pdf
false
Publication
unknown
unknown
<Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="62f25a71-7af7-40f2-a53d-e49fad1a6592">
<Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type>
<Language>eng</Language>
<Title>Turbine inlet non-uniformities and unsteady mechanisms</Title>
<PublishedIn>
<Publication>
</Publication>
</PublishedIn>
<PublicationDate>2015</PublicationDate>
<Authors>
<Author>
<DisplayName>Jedamski, Devon (Devon James)</DisplayName>
<Affiliation>
<OrgUnit>
</OrgUnit>
</Affiliation>
</Author>
</Authors>
<Editors>
</Editors>
<Publishers>
<Publisher>
<DisplayName>Massachusetts Institute of Technology</DisplayName>
<OrgUnit />
</Publisher>
</Publishers>
<License>http://dspace.mit.edu/handle/1721.1/7582</License>
<Keyword>Aeronautics and Astronautics.</Keyword>
<Abstract>The effect of axial turbine stage inlet non-uniformities are examined through two model problems: wake attenuation and hot streak processing. In the first, twodimensional calculations (RANS and URANS) are used to identify the mechanisms contributing to upstream stator wake attenuation through a turbine blade row. For a representative turbine rotor, pitch and time-averaged wake attenuation by 74% percent is demonstrated at one quarter chord downstream of the trailing edge. Near the pressure surface, the wake stagnation pressure increases by up to 42% above the freestream stagnation pressure. The mechanisms identified are a localized reduction in flow-through time for wake fluid near the pressure surface, compared to the freestream, and an unsteady pressure field (Op/&t) in the rotor reference frame that increases work extraction in the freestream relative to wake fluid. For the second model problem, three-dimensional calculations (RANS and URANS) identify a difference in turbine efficiency sensitivity to thermal distortion between a geometry with no tip gap and a geometry with a finite tip gap. The turbine with a tip clearance is 2.5 times less sensitive, in terms of efficiency decrease, to an inlet hot streak. For the tip gap and no tip gap geometries, the efficiency drops by 0.75% and 1.86% respectively for a peak temperature non-uniformity equal to 0.6 times the combustor temperature rise. The difference in efficiency decrease, due to hot streak, between the two geometries is linked to a reduction in tip leakage mixing losses caused by changes in relative rotor inlet flow angle with and without hot streak.</Abstract>
<Access xmlns="http://purl.org/coar/access_right"
>
</Access>
</Publication>