A Study on Buoyancy Driven Turbulent Flow Associated with Radiation in Cavities Partially Filled with Blockages

Iyi, Draco (2013) A Study on Buoyancy Driven Turbulent Flow Associated with Radiation in Cavities Partially Filled with Blockages. Doctoral thesis, Northumbria University.

Preview

PDF (PhD thesis) iyi.draco_phd.pdf - Accepted Version Download (6MB) | Preview

Abstract

Fluid flow and heat transfer in cavities partially filled with disconnected blockages is important in the design of a wide range of industrial and engineering applications such as thermal management of indoor environments, cooling of electronic panels, drying of agricultural products, stacking of items in cold storage etc. The flows in such confined spaces develop as a result of temperature and concentration gradient which is further complicated by the interactive effects of turbulence and radiation. The aims of this research are to explore the detailed heat transfer and flow field inside cavities partially filled with solid blockages and, in particular, to address the uncertainties associated with turbulence models, to quantify the influence of double diffusion and to study the effect of surface properties.

To achieve the above aims, a systematic numerical investigation has been carried out by validating the computational results against reliable experimental data available in open literature. A selection of turbulence and radiation models has been employed to scrutinise the effects of the above flow physics. An experimental set up capable of establishing low Rayleigh number buoyancy driven flow in a rectangular cavity containing cylindrical blockages was designed and fabricated to obtain temperature data. A series of experiments was conducted to obtain reliable temperature distribution at various positions in the flow domain and on the surfaces of the blockages. This set up also allowed us to study the proximity effect of blockages which has not been reported elsewhere. It has been found that the choice of turbulence model remains to be an important issue and should be given due consideration for natural convection flow with a high Rayleigh number. The results from the parametric study on the specification of passive thermal boundary conditions reveal that the experimental temperature profile is the most accurate boundary condition for passive walls in relation to the adiabatic and linear temperature profiles. Experimental benchmark temperature data evaluated at various positions in the cavity with and without blockages are presented and some of them are compared with CFD simulations.

Finally, as an example of the application of the research methodology, a detailed numerical modelling was conducted on a Double-Skin-Façade which is known to reduce energy consumption in building and has become popular in recent years. The current methodology has been applied to establish a number of parameters in connection with the design and performance of DSF which are believed to be useful to practitioners.

Actions (login required)

View Item

Downloads