Analysis on Laminar Chaotic Mixing Based on Configuration of Streak Lobes in an Impeller-Agitated Vessel

作者：Hashimoto Shunsuke^*; Osaka Ryota; Kawamata Makiko

来源：Industrial & Engineering Chemistry Research, 2012, 51(19): 6939-6947.

DOI：10.1021/ie203036n

In the case of laminar chaotic mixing in a stirred tank, our previous study theoretically revealed that the streakline originating from the tip of the impeller provides the formation of a mixing pattern and its outline comes close to the configuration of the streakline with respect to time. In the present study, the laminar chaotic mixing in a 3-D stirred tank was investigated experimentally by use of a new index, "streak lobes", which were equivalent to the region surrounded by the streakline. The streak lobes were created by the minute perturbation wave (traveling wave) that is generated by the rotation of the impeller blade in a stirred tank. The amplitude and frequency of their traveling waves were dominant for the size (width and area) and/or number of streak lobes. The experimental results demonstrated that the large area of streak lobes in the 3-D velocity field resulted in good chaotic mixing, even if the number of streak lobes is small. In addition, the fluid exchange between top and bottom regions in the stirred tank occurred rapidly in the case where the streak lobes could come and go between two regions. It was suggested that the streak lobes can play an important role as an index whether or not good chaotic mixing occurs in the stirred tank. The present study proposed that the control of the size and/or number of streak lobes adjusting the amplitude and frequency of the traveling wave caused by impeller rotation resulted in a shortcut to enhance laminar chaotic mixing.

• 出版日期2012-5-16