Spatially resolved experimental analysis and modeling of mass transfer from rising gas bubbles under the influence of swarm turbulence with superimposed chemical reaction (DFG SPP 1740)
Photography of the experimental setup. The slide is placed inside the gradient tube of the MRI tomograph. In this, a strong magnetic field orients the nuclei of the sample. Due to this excitation, the sample emits a signal which can be detected by a set of measurement coils. The coils can be moved against each other to trim the signal detection. Cylindrical glass capillaries are used as measurement volume in which the multiphase liquid flows.
Superposition of the volumetric measurement and a model of the capillary. We measured a static phantom, which consists of a cylindrical capillary (I.D. 5mm) filled with water and air. The acquisition time is approx. 12 minutes. The color shows the intensity of the measured water signal while gray represents medium intensity. Coloured areas represent a change in thickness of the liquid layer and could indiciate inhomogeneities of the measurement. Clearly, the top part of the capillary contains trapped air, which is obvious because the water intensity signal is zero.
Comparison of different parameters during a fast imaging measurement sequence. The exposure time of each single image was approx. 50 ms with a 1 second distance between each frame. a) With a spin deflection angle of 60°, the relaxation time of the spin is larger than the time between two frames. This causes a saturation of the signal and a decrease in intensity with measurement progression. b) When the spin deflection is decreased to 10°, the saturation can be reduced. c) An additional measurement of the T2 signal gives high resolution information but also causes artefacts which can only be reduced using sequence optimization.