Isolated mixing regions exist widely in the stirred tank

which is a major obstacle for efficient mixing. In order to increase the mixing efficiency

the method of multiple flow fields coupling

which can bring out fluid chaos

is used to increase fluid mixing efficiency by reducing the isolated mixing regions. The largest Lyapunov exponent and multi-scale entropy are investigated with the aid of Matlab in the coupling of eccentric air jet and rigid-flexible combined impeller system. Meanwhile

the effects of impeller types

impeller off-bottom clearances

air jet flow rates

and the impeller speeds on the mixing performance are analyzed at different eccentricities. The results show that the flow field coupling of the rigid-soft-flow of multi-body motion of rigid-flexible combined impeller and eccentric air jet destroy the symmetry flow in the process of fluid mixing and made more fluid into the chaotic state. The LLE of rigid-flexible combined impeller is larger than that of rigid impeller. The LLE of rigid-flexible combined impeller compared with the other three types agitators (IRDT

RDT

RF-IRDT) increases 42.8%

27.0%

and 6.9%. When the eccentricity of the air jet is equal to 0.6

the maximum LLE value is 6.5%

2.4%

17.6% and 25.1% which is higher than the other eccentricity (0.8

0.4

0.2

0). The results of this study can provide the theoretical basis for the optimal design of rigid-flexible agitator.