Bubbly Flows Analysis, Modelling and Calculation

The book summarises the outcom of a priority research programme: 'Analysis, Modelling and Computation of Multiphase Flows'. The results of 24 individual research projects are presented. The main objective of the research programme was to provide a better understanding of the physical basis for multiphase gas-liquid flows as they are found in numerous chemical and biochemical reactors. The research comprises steady and unsteady multiphase flows in three frequently found reactor configurations, namely bubble columns without interiors, airlift loop reactors, and aerated stirred vessels. For this purpose new and improved measurement techniques were developed. From the resulting knowledge and data, new and refined models for describing the underlying physical processes were developed, which were used for the establishment and improvement of analytic as well as numerical methods for predicting multiphase reactors. Thereby, the development, lay-out and scale-up of such processes should be possible on a more reliable basis.

Detailed experimental studies on gas-liquid bubble flow in bubble columns with and without recycle.- Basic experimental investigations on the hydrodynamics of bubble columns.- Examination ofbubble collisions and coalescence in bubbly flows.- PIV-Study on bubble interaction and wakes in multiphase flows.- Dynamics of the flow in bubble column reactors.- Improved model for the calculation of homogeneous gas-liquid flows.- Experimental and theoretical investigation of bubble break-up and coalescence in bubbly flows.- Experimental investigation and modeling of air/water flows in vertical pipes.- Experimental and theoretical investigation of instationary bubble flow and mass transfer in a bubble column.- X-ray based particle tracking velocimetry for bubble columns with high void fraction.- Multi-level modelling of dispersed gas-liquid two-phase flows.- Direct numerical simulation of mass transfer between rising gas bubbles and water.- Analysis of bubble interactions in bidisperse bubble swarms by direct numerical simulation.- Finite element discretization tools for gas-liquid flows.- A transport equation for the interfacial area in bubble columns using a population balance approach.- Flow fields in bubble columns with mass transfer.- X-ray computational tomography measurement of 3-phase flow in bubble columns.- Euler/Lagrange calculations of gas-liquid-solid-flows in bubble columns with phase interaction.- Local parameters of three-phase flow in column reactors with high disperse phase hold-up.- Model fundamentals for the design of three-phase loop reactors.- Simultaneous measurement of the local liquid and the local solid velocities.- A numerical model of dispersed two phase flow in aerated stirred vessels based on presumed shape number density functions.- Influence of theoperating conditions on the bubble characteristics in an aerated stirred vessel.- Bubble dispersion in aerated stirred vessels.- PDA measurements and numerical simulation of turbulent two-phase flow in stirred vessels.