Study on the flow structure in an aerated flat apparatus using laser Doppler anemometry

For the verification of numerical simulations of bubbly flows, a flat apparatus with a rectangular cross section was proven to be a useful tool. A flat bubble column has a less complex flow structure and laser Doppler anemometry (LDA) an optical measurement technique, provides a visual accessibility of all flow regions. At certain operating conditions, the characteristic dynamic flow behavior was well suited for the validation of dynamic flow models. In cylindrical bubble columns, flow structures with low frequencies occurred. Local measurements of liquid phase velocity and gas holdup showed the characteristic frequencies of ≤ 0.1 Hz. The low frequency fluctuations had a chaotic behavior and their frequency range was much broader. The filter design might then affect the separation phenomena, and an alternative to filtering is probably necessary for cylindrical bubble columns.