Studies on the Flow Patterns of Liquid, in the Cylindrical Mixing Vessel, for the Lamnar and Transitional Flow Range

Abstract

The flow patterns of agitated liquid in the cylindrical mixing vessel without baffles were measured by the photographic method. for the range extending from the laminar to the so-called transitional flow region.As the authors have already made clear the flow patterns of liquid and the discharging performance of impellers, for the turbulent flow range1), they are now able to discuss these over the wide range of Reynolds Number.Some of the experimental results are shown in Figs. 4, 5 and 6.The results revealed by the authors on the distribution of liquid velocity are as follows:In the range where Reynolds Number is very small, the liquid velocity is considerably high in the neighborhood of the impeller, which, however, rapidly decreases as the distance from the impeller increases. On the other hand, in the range where Reynolds Number is big, the liquid velocity is kept high by the transmission of the momentum, even in a place far from the impeller, since the secondary circulation flow occurs as shown in Fig. 6 (c) and the liquid flow becomes turbulent, keeping the velocity distribution nearly uniform throughout the vessel.Of the discharge flow from the tip of the impeller blades, which causes the secondary circulation, the non-dimensional quantities, Nq1 and NP/Nq1, are defined as in the previous report1). These values have been calculated and the characteristic curves of discharging performance obtained for various types of impellers (Cf. Table 1), as shown in Fig. 7.Furthermore, the relations among flow pattern, discharging performance and power consumption (NP-Re relation) are discussed.