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Application of a population balance approach for polydispersed bubbly flows

Krepper, E.; Beyer, M.; Frank, T.; Lucas, D.; Prasser, H.-M.

A population balance model was developed in close cooperation of ANSYS-CFX and Forschungszentrum Dresden-Rossendorf and implemented into CFX-10 (Frank et al. 2005, Krepper et al. 2007). The current paper presents the application of the model to upward flow in vertical pipes for air/water and for steam/water bubbly flow. Finally the application to a bubbly flow around a half moon shaped obstacle arranged in a 200 mm pipe is shown (see Frank et al. 2007).
Applying the inhomogeneous MUSIG approach a more deep understanding of the flow structure is possible. For upward two phase flow in vertical pipes the core peak in the cross sectional gas fraction distribution could be reproduced very well. For complex flows the general structure of the flow could be well reproduced in the simulations. This test case of the obstacle demonstrates the complicated relationship between size dependent bubble migration and bubble coalescence and break-up effects for real flows. While the closure models for bubble forces, which are responsible for the simulation of bubble migration are in agreement with the experimental observations, clear deviations occur for bubble coalescence and fragmentation. The presently applied models describing bubble fragmentation and coalescence could be proved as weak points in numerous CFD analyses of vertical upward two phase pipe flow. Further work on this topic is considered for future investigations.

Keywords: Bubbly flow; CFD; Non drag forces; bubble break up; bubble coalescence; population balance; validation

  • Contribution to proceedings
    International Conference on Multiphase Flow - ICMF 2007, 09.-13.07.2007, Leipzig, Germany
    Poster No PS6_6
  • Poster
    International Conference on Multiphase Flow - ICMF 2007, 09.-13.07.2007, Leipzig, Germany

Permalink: https://www.hzdr.de/publications/Publ-9686
Publ.-Id: 9686