EXPERIMENTAL-STUDY OF LAMINAR BUBBLY FLOWS IN A VERTICAL PIPE

Measurement of bubbly two-phase flow parameters in a vertical pipe wer e performed. To keep the pipe Reynolds number below that for single-ph ase turbulent transition, a water-glycerin solution was used as the te st liquid. Local void fraction and liquid velocity profiles along with the wall shear stress were measured by an electrochemical method. Exp eriments were made with bubbles of two different sizes. As the gas flo w rate was increased, a gradual development of the liquid velocity pro file from the parabolic Poiseuille flow to a flattened two-phase profi le was observed. The evolution of the wall shear stress and of the vel ocity fluctuations were also quantified.