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" A Numerical Study of Heat Transfer in a Square Channel With and Without Bleed Holes Roughened With Staggered Square Ribs "
Su, Jiaying
Taslim, Mohammad E.
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Latin Dissertation
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| Language of Document
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English
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| Record Number
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1104410
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| Doc. No
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TLpq2229436096
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| Main Entry
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Su, Jiaying
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Taslim, Mohammad E.
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| Title & Author
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A Numerical Study of Heat Transfer in a Square Channel With and Without Bleed Holes Roughened With Staggered Square Ribs\ Su, JiayingTaslim, Mohammad E.
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| College
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Northeastern University
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| Date
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2019
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| student score
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2019
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| Degree
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M.S.
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| Page No
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57
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| Abstract
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This thesis investigates the internal and external cooling effects on a turbine blade when employing bleed holes between 90° staggered square ribs in the cooling channel of an airfoil. These geometries could have numerous applications in an adjacent channel near the leading edge of the blade to supplement external film propagation from the vortex chamber, while also aiding in internal cooling. Numerical studies were conducted to determine the heat transfer distribution within the cooling passage, as well as exiting mass flow through the bleed holes. Two configurations of bleed holes were studied: (1) bleed holes were placed in between 90° staggered square ribs on one side (Configuration 1), (2) bleed holes were placed in between 90° staggered square ribs on both sides (Configuration 2). Note that the partition walls of the cooling channel did not have any features. The local Nusselt and Reynolds numbers were determined by prescribing a known heat flux on all the walls of the channel to determine the local fluid properties. This investigation revealed that even though a portion of the air was relieved through the bleed holes, there was still significant enhancement in heat transfer when compared to the Dittus-Boelter smooth wall correlation. The resulting heat transfer properties within this corrugated geometry reported lower heat transfer coefficients than the case where there are no bleed holes; however, these geometries offer advantages to transpiration cooling on the blade. Regarding external cooling, Configuration 1 exhibited a linear reduction of mass flow rate through each bleed hole, while Configuration 2 exhibited nearly uniform mass flow rate through all bleed holes. Regarding internal cooling, the local Nusselt numbers for both configurations increased with increasing inlet Reynolds number. Additionally, the two configurations reported friction factors that had similar decreasing trends as the case without bleed holes; however, they had different magnitudes due to continual pressure loss through the bleed holes. This suggested that the flow domain remained largely preserved within the core of the test section. Experimental investigations should be conducted to support the results and correlations.
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Mechanical engineering
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