Fundamentals of gas-liquid and gas-liquid-solid flow in a bubble column and in a simple shear flow device

This thesis deals with fundamentals of gas-liquid and gas-liquid-solid flows in chemical and environmental industry and applications. The study contains three parts covering bubble size and its distribution in a bubble column, fluids flow and bubbly motion in a simple shear flow device and gas-liquid-solid flow in a column.; In the first part of the thesis, the experimental and computational study on bubble size and its distribution in the column was carried out. Bubble size measurements were conducted by high speed CCD cameras. A LabVIEW based codes for measuring bubble size were developed. A user-define-function subroutine of scalar equations for sub-bin bubbles incorporating with bubble break up and coalescence mechanism was implemented into Eulerian multiphase flow approach within the FLUENT(TM) code for analyzing the gas and liquid flows in the bubble column. Bubble size and number density and their distributions in horizontal and vertical direction for different superficial gas velocities were analyzed. The time series and spatial distributions of air and liquid velocities were evaluated and the results were presented and discussed.; In the second part of thesis, the fluid flow and bubble motions in a vertical simple shear flow device were investigated. Particle Image Velocimetry(PIV) was used to measure the liquid velocity field in the simple shear flow device under various shearing rates. The influence of flow Reynolds number on the liquid velocity profile was studied. The critical Reynolds number for laminar to turbulent transition was found by experiments. Air bubble motion at the midsection of the simple shear flow device was analyzed. The effect of bubble ejection frequency and shearing rate on the shear flow field was investigated. The experimental data for turbulence intensities, u'2 , v'2 and Reynolds stress u'v' were obtained for the different bubble ejection frequencies. An Eulerian volume of fluid (VOF) computational model for the flow condition in the 3-dimensional simple shear flow device was also developed. The simulated flow fields were compared with the experimental data and discussed.; In the third part of the thesis, an Eulerian-Eulerian computational model for gas-liquid-solid flows in three phase slurry reactors was developed by using User-Define-Function subroutine of scalar equations in which the interaction between bubble-bubble, bubble-liquid and particle-liquid was implemented for analyzing the gas-liquid-solid flows in the column. The simulation results were compared with the available experimental data. The particle motion was characterized by the granular temperature (turbulent kinetic energy of the particles) in horizontal direction. The Sauter mean bubble diameter in the horizontal and vertical direction was analyzed and discussed.