底吹き円筒容器内水-空気系気泡噴流の有効動粘度と気泡の有効拡散係数

抄録

The effective viscosity ν_e and effective diffusivity D_e of bubbles in vertical bubbling jet in a cylindrical vessel were determined from governing equations based on the boundary layer approximation and the Boussinesq approximation. These conditions were satisfied in the buoyancy region in vertical bubbling jet. Gas holdup and mean bubble rise velocity needed in calculation of ν_e and D_e were measured with a two element electro-resistivity probe, and the mean velocity of water with laser Doppler velocimeter. The values of ν_e and D_e were almost the same on the jet axis in the buoyancy region and increased with an increase in injected gas flow rate. The radial profile of ν_e was parabolic and that of D_e was almost uniform across the bubbling jet. The profile of ν_e was different from the profile of ν_e in single-phase turbulent free jet.