Publikationsrepositorium - Helmholtz-Zentrum Dresden-Rossendorf

During the last years a modelling framework for CFD-simulations of poly-disperse bubbly flows using the Euler-Euler approach was formulated at Helmholtz-Zentrum Dresden – Rossendorf (HZDR). The main idea behind is to achieve a consolidation of multiphase CFD by having a fixed set of closures applicable for a range of expected local flow conditions (Lucas et al., 2016). The corresponding closures concern the momentum transfer between liquid and gaseous phases, the influence of gas on the liquid phase turbulence and models for bubble breakup and coalescence (Rzehak et al., 2015, Liao et. al 2015). This baseline model was applied to a large variety of bubbly flows as round and rectangular bubble columns, bubble plumes, airlift reactors and upwards vertical pipe flow with different pipe diameter without any modification or tuning. In the results a good or at least acceptable agreement was found for most of the cases, but for some other cases also clear deviations were observed. Such deficiencies have to be investigated more in detail to improve the models step by step.
In this work the model is applied to co-current upward, counter-current and co-current downward vertical pipe flows recently measured at the HZDR TOPFLOW facility using ultrafast X-ray tomography. The results are discussed in detail.