エアレーション槽内気泡噴流の流動挙動 (<小特集>混相流の数値シミュレーションと新技術)

抄録

Laser Doppler velocimeter measurements were made to investigate bubbling jet characteristics in an aeration tank at a pressure of 200kPa. The data were compared with previous measurements at atmospheric and reduced pressures. Bubble frequencies at the nozzle outlet were correlated with the mass flow rate of gas rather than the volumetric flow rate. In the far field where the buoyancy force of bubbles prevails, the axial and radial distributions of the mean velocity components, the r. m. s. values of turbulence components, the Reynolds shear stress and the skewness and flatness factors of the turbulence components obtained at an elevated pressure agreed well with those obtained at the atmospheric pressure for the same volumetric gas flow rate. Consequently, the liquid flow characteristics including the turbulence structure in the far field are not influenced by an increase in surface pressure as long as the volumetric gas flow rate is the same.