Impact of Baffle Geometry and Baffle Number on Vortex Formation in Single‐Stage Radial Stirring Systems

In stirred tank reactors, vortices are currently predicted using an outdated dimensionless baffle index that does not correspond to state of the art in science and technology. However, it is extremely important to know when a vortex occurs because they have various advantages and disadvantages. For this reason, knowledge about vortices, especially in reactor systems with baffles, is of great importance to the production and process industry. In order to close this significant knowledge gap, this study presents comprehensive and detailed results from experiments conducted on a laboratory scale of 110 mm for the evaluation, prediction, or prevention of vortices in a Reynolds number ranging from 1,000 to 45,000, as well as providing a definition of vortices for the first time. For the investigations, two single‐stage radial stirrers, the Rushton turbine and the curved‐blade impeller, with varying numbers of baffles between zero and six, and different baffle geometries (rectangular, cylindrical, and triangular) are analyzed in water. The power consumption, vortex characteristics, and influence of the baffled state are examined. The vortices present are detected using MATLAB macros and described mathematically with a fourth‐degree polynomial function. The obtained vortex shape (depth, width, and volume) is presented as a mathematical relationship. Furthermore, this study provides, for the first time, dimensionless values for vortex depth, width, and volume. These dimensionless values can be used as design rules, assistance, or recommendation. This allows more accurate predictions about vortices in large reactors in order to simplify the design and better positioning of internal installations to make stirred tank reactors more economical and sustainable in the future.