Characteristics of fluid and surface fluctuation of liquid metal under gas injection

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Gas injection in liquid metal plays very important role in metal-refining processes, so that it is necessary to investigate the characteristics of free surface fluctuation and fluid flow in order to make clear refining mechanisms. The purpose of the present study is to investigate the characteristics of turbulent flow including wavy motion of the free surface and to study two phenomena related to metal refining, dispersion of buoyant particles (inclusion particles) in liquid and turbulent mass transfer between gas and liquid. The following studies have been made :1. Measurement of surface fluctuation and turbulent flowThe contour of the free surface, amplitude of fluctuation, fluctuation frequency, fluctuating velocities of free surface and turbulent velocities have been measured in a water-model vessel. The results on free surface movements have been discussed in relation to the fluid flow characteristics.2.Development of a simulation model of fluid flowA computer simulation model has … More been developed to estimate the turbulent flow in gas-injected vessel considering the dispersion of bubbles by turbulent diffusion and the turbulence generation due to the slip velocity between bubbles and liquid. The computed values of energy-dissipation rates agreed well with the values of input-energy density for stirring.3. Analysis of buoyant particle distribution in water vesselHollow glass beads were input in a gas-injected water vessel and the distribution of particles was observed. The critical gas-flow rate beyond which particles at the free surface begin to disperse into bulk water has been clearly observed and correlated with the size of particles. The estimated particle distributions based on the numerical calculation of particle transport in turbulent flow were agreed with the observed results by considering the resistance of particle entrainment from free surface.4. Analysis of gas-liquid-mass transferThe eddy-cell model which considers the surface renewal by turbulent eddies has been applied to estimate the volumetric coefficient of gas-liquid-mass transfer. Although calculated values of volumetric coefficients in bubble-dispersion zone agreed with the observed values previously obtained by us, the estimated values at the free surface have to be modified by considering the effect of the wave on the free surface. Less