ANALYSES OF THE RADIAL DISTRIBUTIONS OF AVERAGE VELOCITY AND TURBULENT VELOCITY OF THE LIQUID-PHASE IN BUBBLY 2-PHASE FLOW

The radial distributions of average velocity and turbulent velocity of the liquid phase are predicted based on the correlations of the bubble dispersion coefficient, turbulent diffusivity of liquid and the mixing length of two-phase flow previously derived by the authors. The radial distribution of average liquid velocity was predicted using basic equations of mass and momentum conservations for both phases. The prediction generally agrees with experimental data, which show a flattened radial distribution compared with the single-phase flow at the same liquid volume flux. The radial distribution of turbulent velocity was predicted -using the basic equation of turbulent velocity for the case where turbulent velocity in two-phase flow is larger than single-phase flow turbulent velocity for the same liquid flux. The prediction successfully predicted the flattened distribution of turbulent velocity. Detailed consideration was given to the contributions of generation by velocity gradient, dissipation, diffusion and generation by a bubble to the turbulent velocity distribution, and it was shown that the turbulence generation by a bubble is predominant in the central region of a bubbly two-phase flow.