Study of bubbling fluidization dynamics via Digital Image Analysis TechniqueAdvances in Fluid Mechanics VII

In the area of chemical engineering, fluidization is a widely employed technology for a number of industrially important processes. A sound understanding of the mechanisms governing the complex flow phenomena involved in a fluidized bed still remains an open technical and scientific issue. The principal difficulty in analysing fluidization quality and bubble dynamic is concerned with the possibility of measuring or predicting the physical and geometrical properties of gas bubbles chaotically rising in a solid granular medium. In recent years the use of Computational Fluid Dynamics (CFD) has been significantly increasing to simulate multi-phase flows. It is invariably emphasized that a necessary step towards the development of reliable fully predictive CFD models is an extensive experimental validation of the simulation results. On the above basis, the present work focuses on the statistical analysis of the behaviour of a 2-D fluidized bed operating under bubbling and slugging conditions. Experimental data are collected by the means of a purposely developed Digital Image Analysis Technique (DIAT). DIAT is capable of measuring several bubbles properties simultaneously. Moreover it could be used without any modification for computational data analysis, thus providing the answer to the need for close comparison between experimental and computational data. In fact, in many cases, direct experimental validation of CFD simulation is difficult and cumbersome, since different level of detail is available in experimental and computational investigations. In this work, the development of an image analysis technique available for both experimental and computational data does allow direct and effective quantitative comparison