Pseudo turbulence in laminar and transitional regimes of an upward bubble flow in a pipe
L.S. Timkin, R.S. Gorelik
Kutateladze Institute of Thermophyhsics SB RAS, Novosibisrk, Russia
Keywords: bubbles, gas-liquid flow, proper liquid turbulence, pseudo turbulence, wall friction stress, friction pulsations
Abstract
In a bubble flow, both proper turbulence of liquid and pseudo turbulence induced by the bubbles are present. Total two-phase turbulence of the flow is simultaneously determined by the interaction of these two components. The experimental values of the average friction stress and its pulsations obtained by eight double electrodiffusion friction sensors located uniformly in one section along the pipe perimeter are presented. The gas phase is represented by monodisperse bubble mixtures with average diameters of 1 and 2 mm and a volumetric gas content of up to 20%. To modify the Reynolds numbers for a bubble, two working solutions with different viscosities were used. The average flow velocity of liquid did not exceed 1 m/s. Flow regimes with deviations from the Sato hypothesis on the additivity of pseudo turbulence and proper turbulence of liquid were detected. At transitional Reynolds numbers of the flow and small Reynolds numbers of a bubble, total turbulence is determined by pseudo turbulence, and there is no the influence of singe-phase turbulence.
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