NONUNIFORMITY OF GAS DISPERSION IN TURBINE-GENERATED VISCOELASTIC CIRCULATION FLOW

Gas dispersion has been analysed experimentally by measuring local gas hold-up in two lab-scale conventional turbine-agitated vessels loaded with viscoelastic fluids. The gas hold-up radial profiles obtained in various axial positions close and far from the impeller reveal high n on-uniformity of gas dispersion. Nonuniformity is quantified and relat ed to elasticity, shear dependent viscosity, shear rate, first normal stress difference coefficient and type of fluid. The low values of gas hold-up obtained for the vessel central area are interpreted as hinde red gas dispersion caused by the flow pattern specific for the viscoel astic properties of the circulating fluid. The paper is complementary to the effort for collecting up data for benchmarking numerical CFD si mulations (Kumar et al., 1997).