Mixing power were characterized by torque sensor. The largest Lyapunov exponents were computed by Matlab software. The fluid mixing performances were observed by the fluid field's visualization technology. A comprehensive experimental study on the effects of impeller type

the distance between impeller and bottom

the length of flexible wire

and the diameter of flexible wire on the number of mixing efficiency (Ce)

and the largest Lyapunov exponents (LEmax) was carried out. Results showed that

single-wire flexible impeller can regulate and control the flow field structure and the way of energy dissipation

and effectively enhance the chaotic mixing. At rotation speed 120 r·min−1

compared with the traditional rigid impeller

Ce was decreased by 87.4% and LEmax was increased by 53.2% with single-wire flexible impeller

Ce was decreased by 43.8% and LEmax was increased by 10.8% compared with single-wire rigid impeller. In addition

at the same agitation speed

the longer the flexible wire

the more conducive to the chaotic mixing

but its power consumption would also increase obviously. The diameter of flexible wire was measured at 0.8 mm

while Ce was less than the others and LEmax was larger than the others

which indicated that the degree of chaotic mixing was the largest in the case. Increasing the diameter of flexible wire led to the increase of fluid motion irregularity and the degree of chaotic mixing. If the diameter of flexible wire is more than 0.8 mm

the disturbance of flexible wire was reduced

which was close to the traditional rigid impeller

resulting in the decrease of chaotic mixing characteristics. It was not conducive to fluid mixing while the distance between impeller and bottom was too high or too low

the optimal distance between impeller and bottom was at 0.25T (T was used to express the inner diameter of stirred vessel).