Measurement and simulation of hydrodynamics and mixing time in stirred tank with submerged long-short blades impeller

The hydrodynamics and mixing characteristics of long-short blades (LSB) impeller have been investigated by particle image velocity (PIV), planar laser induced fluorescence (PLIF) and large eddy simulation (LES). The prediction accuracy of LES was assessed by the velocity distribution, tracer concentration distribution and power number. The results demonstrate that there are few stagnation zone and no zone effect in LSB stirred tank. The special design of LSB impeller leads to the up-flow in the lower region and down-flow in the upper region, which makes the pumping number of LSB impeller is better than that of single RT and dual RTs. In addition, the feed location and detecting location do not affect the homogeneity of the local mixing process, that is, the tracer diffuses rapidly to the whole tank in the axial and radial directions. The dimensionless mixing time correlation equation of LSB impeller is established.