Turbulent flow inside a cylindrical baffled stirred vessel is studied experimentally for different Reynolds numbers. A set of speed was selected ranging from 100 rpm to 350 rpm. These speeds gave high turbulence but without significant surface vortex formation. Vector field's maps and contours of time averaged velocities, for both radial and axial components in the impeller stream of a vessel stirred by a Rushton turbine, were determined by means of 2D PIV technique. This study reveals the importance of choosing the whole flow field of the entire vessel in order to provide comprehensive understanding of the flow pattern and mixing conditions which is essential for reliable design.

Abstract. The aim of this paper is to study experimentally by particle image velocimetry system (PIV) the effect of the pumping direction introduced with a 60° pitched blade turbine. In fact, an Up-and a down-pitched blades turbine were used. The particle image velocimetry technique is equipped with a double pulsed Nd:YAG laser, a CCD camera resolution and a mini-synchronizer. Therefore, several results were carried out to investigate the hydrodynamic structure and the energetic parameters in a stirred vessel.

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This work is aimed at studying the hydrodynamic structure in a cylindrical stirred vessel equipped with an eight-curved blade turbine. Flow fields were measured by two-dimensional particle image velocimetry (PIV) to evaluate the effect of the curved blade turbine. Velocity field, axial and radial velocity distribution, root mean square (rms) of the velocity fluctuations, vorticity, and turbulent kinetic energy were presented. Therefore, two recirculation loops were formed close to the free surface and in the bottom of the tank. Moreover, the highest value area of the vorticity is localized in the upper region of the tank which follows the same direction of the first circulation loop. The turbulent kinetic energy is maximum at the blade tip following the trailing vortices.

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