Turbulence in bubble flows
Grant number
SO 204/13-1
Project title
Invenstigation and modelling of turbulence in bubble columns
Project leader
Prof. Dr.-Ing. habil. Martin Sommerfeld
Realized by
Dr. rer. nat. M. Göz
Dipl.-Ing. D. Bröder
Keywords
turbulence, bubble columns, modelling of source terms, experiments
Short description of the project
The analysis and modelling of turbulence in bubbly flows using the bubble column as an example is subject of this research project. The fluid flow and the turbulence in this widespread apparatus is induced only by the bubble rising. That's why it is necessary for the planned development of a numerical calculation approach basing on the time averaged Navier-Stokes equations in connection with the k-epsilon turbulence model to introduce appropriate source terms into the conservation equations of the fluid phase to comprehend the influence of the bubbles on the fluid phase. Especially the turbulence induced by the bubble rising is not well understood up to now and that's the reason why only little knowledge about the modelling of this effect in the conservation equations for the turbulent kinetic energy k and its dissipation epsilon is available. This is the emphasis of the research project and it is planned to develop suitable source terms for the modelling of bubble induced turbulence. Making this possible direct numerical simulations of the motion of bubble swarms basing on the time dependent solution of the three dimensional Navier-Stokes equations and a tracking algorithm should be used for the calculation of the motion of bubble contours. Besides, experimental investigations of a bubble column by means of Particle-Image Velocimetry (PIV) and phase-Doppler anemometry should be carried out to check the direct numerical simulations and to validate the modelling of the source terms of the equations for the turbulent kinetic energy and its dissipation. First of all, the investigations should be focussed on the aeration with fine bubbles and low gas contents.
