| Summary: | Natural convection is a common phenomenon occurring both in nature and in industrial applications. Among the various confined enclosures, the rectangular cavity (empty or partitioned) is the most extensively studied enclosure because many engineering geometries can be simplified to this configuration. Natural convection in a rectangular cavity is also a very good vehicle for both experimental and theoretical studies. In experimental terms, the geometry of the rectangular cavity is simple and its boundary conditions are relatively easy to realise so that researchers can focus on the measurements of important quantities such as velocity and temperature profiles. In numerical terms, the flow phenomena in the cavity are so complicated and so plentiful that they intrigue both physicists and engineers. The first part of the thesis introduces the background of this project and an extensive review of the available literature. The literature review is divided into two parts. The first part presents an overview of natural convection in standard cavities with particular emphasis on previous studies pertaining to the simultaneous measurement of local velocity and temperature. The second part reviews and discusses previous studies, especially in the turbulent flow region, in natural convection in partitioned rectangular cavities. The experimental and numerical results are compared. Problems encountered in earlier studies are discussed. A proposal for the present study is given at the end of this part, which is then followed by the mathematical description and definition of the problem. The second part of the thesis introduces the existing experimental system at South Bank University together with the modifications made to suit the present study. The third part of the thesis presents the experimental results, which are then compared with earlier work. The thermal and fluid flow fields were systematically surveyed. The experimental contour plots of T, T', u~, v~ and u'v' and the velocity vector plots are reported for the first time for turbulent natural convection in both standard and partitioned square cavities. In addition to these quantities, the experimental turbulent quantities, u'T' and v'T', are also reported for the first time for natural convection in a standard square cavity. Also, in this part, the results of numerical simulations performed with the commercial software CFX-5.4.1 will be presented and compared with the experimental results. Despite the numerical simulations, this thesis is mainly concerned with the experimental investigation of low level turbulence natural convection in an air filled standard or partitioned square cavity. The experiments were performed with high precision and avoided some of the problems and shortcomings of earlier work. The results form benchmark data for low level turbulence natural convection and are useful for comparison with numerical predictions and CFD code validation and development.
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