Mixing Mechanism of Large Paddle Impeller Based on Streak Line Observation

Streak line patterns of several wide-paddle impellers developed by mixer companies in Japan were observed from laminar to turbulent flow regions. The power consumption of all wide-paddle impellers examined was correlated by using the same correlations as in our previous work, but the mixing mechanism of these impellers in the laminar flow region changed greatly with the kind of impeller. It was found that these wide-paddle impellers had distinctive patterns of streak lines depending on the operation conditions. In particular, liquid height greatly affected the streak line pattern. Furthermore, it was found that the impeller Reynolds number was a parameter that controlled the streak line pattern.