Investigation of Horizontal Velocity Fields in Stirred Vessels with Helical Coils by PIV

Abstract

Horizontal velocity flow fields were measured by particle image velocimetry for a stirred vessel with baffles and two helical coils for enlargement of heat transfer area. The investigation was carried out in a cylindrical vessel with flat base and two different stirrers (radial-flow Rushton turbine and axial-flow propeller stirrer). Combined velocity plots for flow fields at different locations are presented. It was found that helical coils change the flow pattern significantly. Measurements for the axial-flow Rushton turbine showed a strong deflection by the coils, leading to a mainly tangential flow pattern. Behind baffles large areas of unused heat transfer area were found. First results for the axial-flow propeller reveal an extensive absence of fluid movement in the horizontal plane. Improved design considerations for enhanced heat transfer by more compatible equipment compilation are proposed.

Optimization of the Classifying Efficiency of Spiral Jet Mills by Investigating the Flow Conditions and the Grinding Performance

“…Compared to other methods, such as measurements by means of pressure sensors [23], PIV has the advantage of being a non-invasive laseroptical measurement method that does not influence the flow within the mill and thus cannot falsify it. The research group of Prof. Schultz in Krefeld has already gained great experience with this method in previous work and has successfully carried out numerous investigations of flow and mixing processes in various systems [15,24,25].…”

Effect of Impeller Design on Power Characteristics and Newtonian Fluids Mixing Efficiency in a Mechanically Agitated Vessel at Low Reynolds Numbers

“…In review paper [23], the authors showed that the current analyses concentrated on the effect of the multiple-impeller combinations on the required power, mixing time, flow pattern, and mass transfer but there was still a need for future research on multiple-impeller systems in the aspects related to the different impellers geometries, numerical studies on the power and flow field, or studies on solid suspensions. In [24], the authors analyzed horizontal velocity fields in stirred vessels with helical coils using the particle image velocimetry method. They found that the flow pattern generated by the Rushton turbine was dominated by tangential flow structures and the cross-flow structures through cylindrical coils were not observed.…”