A study of turbulent mixing in a turbine-agitated tank using a fluorescence technique
2000 (English)In: Experiments in Fluids, ISSN 0723-4864, E-ISSN 1432-1114, Vol. 28, no 3, 225-235 p.Article in journal (Refereed) Published
Two-dimensional images of (Plane) Laser Induced Fluorescence (PLIF) have been used to study the turbulent mixing process in a model stirred tank. A calibration procedure is presented and discussed in terms of its accuracy. Data from the literature are used for comparison. A pattern-recognition algorithm has been designed to identify and quantitatively describe large-scale structures in the flow. This methodology, called structural analysis, is based on a conditional analysis of the PLIF data and requires the definition of an appropriate structure-detector function which is calculated locally. The mathematical tools developed have been used to study the mixing in a Rushton turbine-agitated reactor. Particular attention is paid to two specific regions of the tank; namely the bulk and the impeller stream regions, at two measured power input (0.3 and 0.7 W kg(-1)). The averaged concentration fields show a common two-dimensional steady circulation pattern. Concentration probability density functions reflect well the instability of the flow in the two regions investigated. The data reveal the non-isotropic distribution of these instabilities around a reference point when the feed port is situated in the bulk region only. In this case, the structural analysis quantitatively shows the presence of a folding of the concentration field. It was found that this phenomenon can last several seconds.
Place, publisher, year, edition, pages
2000. Vol. 28, no 3, 225-235 p.
laser-induced fluorescence, impeller stream, rushton turbine, stirred tanks, reactors, jet
IdentifiersURN: urn:nbn:se:kth:diva-19681ISI: 000086477200004OAI: oai:DiVA.org:kth-19681DiVA: diva2:338373
QC 201005252010-08-102010-08-10Bibliographically approved