NUMERICAL INVESTIGATIONS OF DISCHARGE FLOW AND CIRCULATION FLOW IN AN UNBAFFLED MIXING VESSEL AGITATED BY A PLAIN DISK

Numerical simulations of flow in an unbaffled mixing tank agitated by a plain disk were performed using the CFD software package Fluent. Pre-processing was done using another software package called Gambit, while post-processing was done using an in-house software based on Matlab code. The circulation and discharge flow rates and their respective non-dimensional numbers were investigated. The locus of the recirculation centre has been found to follow a deformed “C” like path, for a centrally located disk. The circulation flow rate was observed to be linearly dependent on the Re and also on the disk size. The range of clearance values, 0.25 ≤ C ≤ 0.50, has been seen to produce the same discharge and circulation flow rates for a given disk size. A smaller clearance C = 0.15T resulted in reduction of Qc & Nqc and & Nqp. The discharge flow rate was seen to be dependent on both the Re and the disk size. The values of Nqc and Nqp found here are smaller than the ones for radial flow impellers. Both the circulation and discharge flow numbers appear not to be constant over the “entire” range of Re.

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