| Summary: | 碩士 === 元智大學 === 機械工程學系 === 93 === This research is to study the phenomena of the flow field induced by partial heat and density differences in an enclosed space between two walls. The enclosed space is confined by isothermal wall to the right and left and protruding outwards. The floor and the ceiling of the space are made of acrylic plates. This research utilized an experimental method to study the natural convection when the structure is placed in different angles (0, 45 and 90 degree). The researching area targets in the flow pattern, change of fluid temperature and density.
The apparatus is a closure made of acrylic plates. Sidewalls have a partially concaved area in center made of copper. The void is fill with cupric-sulphate solution. Two water baths in different temperature provide temperature gradient between walls. We utilized an electrochemical method to produce a gradient in concentration. This will result a boundary layers in concentration between two copper plates. To observe and record the flow pattern inside the apparatus, shadowgraphs and digital camera are used. The photography is used for later analysis. To better understand the flow field structure, we measured the temperature and concentration distribution over the flow field. Finally, measure and analysis the thermo conductivity Sh, Gr,m and Gr,t.
The range of non-dimensional parameters used in this research are listed as the followings:
Pr=7~8 ,Sc=1700~2500 ,s*=0.5 ,Grt=8.9×105~1.34×106 ,Grm=5.47×106 ,
=4.46~6.68
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