Development and qualification of a long-rang microscopic measurement technique to determine the deformation and flow field around bubbles and droplets by means of a single color camera

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Bubbles and droplets play an important role in process engineering. Especially the measurement of their size, shape and trajectory as well as the flow around them with high spatial and temporal resolution is of interest for the characterization and optimization of processes. The scientific aim of the project is therefore the development of an optical measurements technique that enables the precise measurement of these quantities. Small particles suspended in the flow will be observed via a long-range microscope and an additional cylindrical lens will be placed in the optics. Similar to the established Astigmatism Particle Tracking Velocimetry (APTV) method, the deformation of the particle images can be related to their 3D position using a proper calibration. The independent determination of the signals from the droplets and the flow will be performed by using different fluorescent particles in combination with a high-speed color camera. The main benefit is that only one camera is used to prevent errors from complex calibration procedures. In addition the multi-phase flow in apparatus with difficult optical access can be characterized. It is expected that the technique is suited for many useful applications in process engineering and will help to answer complex scientific questions.