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http://hdl.handle.net/11375/8774
Title: | Studies of Jet Flow in Enclosures |
Authors: | Johnson, Andrew David |
Advisor: | Wood, P.E. |
Department: | Mechanical Engineering |
Keywords: | Mechanical Engineering;Mechanical Engineering |
Publication Date: | Jun-1994 |
Abstract: | <p>The flow of jets in confining enclosures has significant application in many engineering processes. In particular, two jet flows have been studied; the impingement of axisymmetric jets in a confined space and a turbulent inlet wall jet in a confining enclosure.</p> <p>The impingement ofaxisynunetric jets in a cavity has been examined using<br />flow visualization, laser Doppler anemometry, and numerical simulations. When the<br />flow fIeld was examined under various geometrical and fluid parameters several flow<br />regions were found, depending on the geometrical and fluid parameters. Initially, a<br />steady flow field existed for all arrangements for Red < -90 but subsequent increments in the fluid velocity caused an oscillating flow field to emerge. The onset of the<br />oscillations and the upper limit of fmite oscillations were found to be a function of the<br />nozzle diameter to chamber dimeasion ratio. Although steady numerical simulations<br />predicted the steady flow field well. steady simulations of the oscillating flow field<br />over-predicted the peak axial velocities. The oscillating flow field is considered to be<br />a class of self-sustaining oscillations where instabilities in the jet shear layer are<br />amplified because of feed back from pressure disturbances in the impingement region.</p> <p>The turbulent wall jet in a cavity has been studied using flow visualization,<br />laser Doppler anemometry (LDA), particle streak velocimetry (PSV) and numerical<br />simulations. Instantaneous PSV measurements agreed well with time averaged LDA measurements. Two dimensional simulations using an algebraic stress turbulence<br />model (ASM) were in better agreement with the experimental data than two and three<br />dimensional simulations using a k - ɛ turbulence model in the wall jet region. A wall jet growth rate was found to be 54% higher than a wall jet in stagnant surroundings due to the enclosure boundaries.</p> |
URI: | http://hdl.handle.net/11375/8774 |
Identifier: | opendissertations/3950 4967 1858906 |
Appears in Collections: | Open Access Dissertations and Theses |
Files in This Item:
File | Size | Format | |
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fulltext.pdf | 16.93 MB | Adobe PDF | View/Open |
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