The dynamics of fluidization are increasingly important to many manufacturing and engineering applications, including molding and coremaking operations, in the foundry. In aggregative fluidizations, there are several abnormalities primarilyrelated to the characteristics of the solid phase, the fluid phase and/or the design of the equipment. Channeling or cohesive flow is an abnormality in which large amounts of gas flow through paths in a sand bed. In through-channeling, the gas flowsthrough the path in the entire nonfluidized bed. In intermediate channeling, only apart of the bed is not fluidized, and the fluid flows through the path in this nonfluidized portion.Shape, density, size and size distribution of the foundry sands, and moisture content are main factors that affect channeling tendencies. Channeling has a large effect on the superficial velocity distribution through the bed. The gas flow through the bedportion of high voidage (dilute phase) is accompanied by separated flow with circular streamlines. All previous investigations concerned the channeling phenomena without considering the complexity of the flow structure. However, the existence of the eddyflow considerably reduces the uniformity (quality) of the fluidized beds.In this paper, we report theoretical predictions and experimental results concerning the through-channeling flow, considering the eddy flow. The analytical solution concentrates on Lavrentyev's model of separated flow. Expressions for the pressure drop,the friction factor and the resistance coefficient, as functions of air velocity and the Reynolds number, have been developed for channeling flow in fluidized beds, based on the previously mentioned model. Experimental data obtained for the frictionfactor and the resistance coefficient, as functions of the Reynolds number, compare well with theoretical predictions. The results of this investigation are helpful in foundry applications, in predicting channeling phenomenon, and choosing optimum flowparameters to avoid it.
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