MODELING MEAN FLOW AND TURBULENCE CHARACTERISTICS IN GAS-AGITATED BATH WITH TOP LAYER

A numerical study is presented of the flow characteristics in a gas-ag itated water bath in the presence of a top layer of dissimilar fluid. Two systems are considered, comprised separately of silicon and normal pentane as the top layer, to simulate slag cover in a real steelmakin g process. The mathematical model involves solution of transport equat ions for the variables of each phase, with allowance for interphase tr ansfer of momentum. Turbulence is assumed to be a property of the carr ier (liquid) phase and represented through solution of additional tran sport equations for the turbulence kinetic energy, k, and its rate of dissipation, epsilon. The model also accounts for turbulence modulatio n by the bubbles through enhancement of the source terms in the equati ons for k and epsilon. The predicted mean and fluctuating velocities, stresses, and turbulence production are generally in the consensus of the experimental data. Both mean flow and turbulence characteristics a re found to be suppressed in the water/silicon system of smaller densi ty ratio, indicating enhanced re-entrainment of the top layer, than th e water/normal pentane system.