Combined volumetric PIV-LIF measurements of the correlation between bubble cluster dyxnamics and mixing in a co-moving frame of a stable/unstable bubble plume

Dynamic interaction of bubbles and cluster formation in swarms have a significant influence on the mixing in reactive bubble columns. These are due to hydrodynamic instabilities on the local scale of the bubble size (wake instabilities , bubble-bubble interaction , change in shape and change of lift forces). In bubble columns where bubble- induced turbulence is dominant these processes are the driving force for mixing. Corresponding correlations of the associated impact on the mass transfer do not exist yet. To investigate these processes a large rotating bubble column (DN 500 , Height 5m) is used with a pulsed gas sparger, where the local dynamics in such a cluster are observed in the co-moving frame during the rise of the plume (cluster of N 10-50 bubbles). The aim of this study is to detect the volumetric flow and concentration field simultaneous within the same sub-volume with temporal tracking of the cluster via combined 3D-PIV/LIF measurement technique. The experimental technique is also adapted to provide boundary conditions as used in high-resolution DNS / LES simulations of flow bubble clusters ( N < 50 ) in a so-called periodic box. Thus a direct quantitative comparison is possible with various working groups in the SPP. Based on the results a suitable transport model is to be derived , which takes into account the local cluster dynamics. The experiments on the bubble swarms are carried out also under the influence of a rotating background motion around the vertical axis in order to investigate the effect of helical instabilities in the swarm.


TU Bergakademie Freiberg
Institute of Mechanics and Fluid Dynamics

 

Project leader
Prof. Dr.-Ing. Christoph Brücker