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Turbulent motion of particles suspended in water in a stirred tank and that of drops supplied to turbulent pipe flow of water are studied with emphasis on their scales. The scales considered are l) sampling time scale: the very small time interval in which the displacement of a particle is measured, 2) measuring time scale: the time-duration during which a continuous measurement is run, and 3) sampling spatial scale: the width of a location in which the displacement of a particle is followed. The effects of these scales on the magnitude of turbulence velocity components are examined, and the magnitudes are evaluated with a set of values of scales which seem most appropriate to each particle motion. The magnitudes are correlated uniformly in both dispersions with particle diameters and energy dissipation rates of surrounding liquid.

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The bubble column is commonly employed as a reactor in industrial processes such as chemical and fermentation processing as well as in the field of waste water treatment. It is often operated under conditions of liquid continuous flow. Correlations in predicting gas holdup in the bubble column with no liquid flow have been proposed by many workers1~5>7). However, the effect of liquid flow rate on gas holdup has not yet been elucidated quantitatively, and the findings obtained have been quite different amonginvestigators owing to the complicated flow situation of the two phases1~3)8).The objective of the present study is to ascertain the flow regimes of gas and liquid, and to obtain correlations useful in predicting gas holdup in both cocurrent and countercurrent flow systems. A criterion of flow regime distinction will be proposed and the effect of liquid flow rate on gas holdup will be examined.