Untersuchung des Einflusses der Transportprozesse auf chemische Reaktionen in Blasenströmungen mittels ortsaufgelöster In-situ-Analytik und simultaner Charakterisierung der Blasendynamik in Echtzeit
By developing new experimental techniques, important contributions to an improved understanding of the interaction between hydrodynamics and chemical reactions in bubble flows shall be achieved. In this (particular) case the experimental methods are based on two systems.One of them is Real-Time Raman-Process-Analysis-System, developed in the first part of the SPP, which will be extended to a mobile system. It allows for a spatially and temporally-resolved in-situ analysis of the liquid phase in the vicinity of the simultaneously observed bubble. In order to determine the chemical composition, the Real-Time-Process-Analysis-System will be used to determine the local substance concentration for each laser pulse at one or more measurement points within a bubble flow at a defined point in time. To achieve this task, a complete Raman spectrum is to be recorded so that chemical reactions with complex Raman spectra can be evaluated and the Real-Time-Raman-Process-Analysis-System is used and applied in a flexible and universal way. Simultaneously with the recording of the Raman spectra, the rising bubbles, bubbles swarms and the surrounding flow field are monitored with high frame rates such as 1000 frames/s, to monitor/track the trajectory and dynamics of the observed rising bubble, e.g., to determine the measurement point or the measurement points for the Raman spectroscopy with respect to the position of the bubble in real-time. This is done by the Real-Time-Raman-Process-Analysis-System by determining the position of the observed bubble of each image sequence in real-time using an integrated image analysis mechanism.Furthermore, a UV/VIS tomographic system shall be developed, which especially is suitable for colored chemical reactions. This system uses several light sources, which can be switched very fast and multichannel detectors. The bubble columns will be illuminated by visible light at a lot of angles. The absorption and concentrations within the voxels of the bubble column are calculated by reconstruction algorithms. With this system the kinetics of chemical reactions in relation to the bubble dynamics will be investigated in detail. In correlation with the observation of bubbles and bubble shapes, the spatially-resolved analysis yields the relevant information about the substance input. In this regard, an extensive automated analysis of bubble shapes will be conducted to measure a large number of bubbles and thereby obtain statistically meaningful results. In this project, bubbly flows, bubbles immobilized by counter-flow with and without the influence of turbulence (grid installations) as well as Taylor-flows within microchannels are to be investigated.
Institut für Parallele und Verteilte Systeme
Prof. Dr.-Ing. Sven Simon