Investigation of the Flow Field in a Rectangular Vessel Equipped With a Side-Entering Agitator

Abstract

The hydrodynamics of stirred vessels with side-entering impellers, which are used in numerous process industries including petroleum, foods, and pulp and paper manufacturing, have received limited attention. In the present work, the flow in a reduced size rectangular tank equipped with a side-entering axial flow impeller, scaled down from the industrial agitation of low consistency pulp fiber suspensions, was investigated using particle image velocimetry (PIV) and computational fluid dynamics (CFD), in the laminar regime (18≤Re≤120). Tuning of the PIV measuring parameters for an optimum capture of valid velocity vectors within a representative portion of the vessel is described. A detailed description of the construction and refinement of the grid and quantification of the discretization error in the CFD results is also presented. The simulation predictions were extensively evaluated by comparing the measured planar flow patterns and velocity fields at various locations in the mixing vessel. Very good agreement was found between PIV measurements and computed velocities confirming the efficiency of CFD in the analysis of mixing systems. The prediction of global mixing parameters was also evaluated. The computed impeller torque and impeller power number agreed very well with experimental measurements over the range of Re studied.