Rational design of impellers in stirred vessels for strengthening the fluid flow and mixing is an important way to achieve efficient and energy-saving mixing. Rigid-flexible coupling impeller can be designed by combination of flexible body and rigid body

possessing multiple-body motion behavior. In this study

CFD simulation and PIV flow visualization were comparatively employed to analyze the difference between rigid impeller and rigid-flexible coupling impeller for fluid flow structure and mixing performance. Results showed that

compared with rigid impeller system

velocity decaying rate was reduced by 25% with rigid-flexible coupling impeller system

because it had the ability to intensify the input energy transportation by flexible part and distribute the input energy in flow field structure effectively. The streamline of the fluid stirred by rigid PBT-6 impeller and rigid RDT-6 impeller had obviously periodic attractor with fractal dimension 1.9046 and 1.9138 respectively. Rigid-flexible coupling impellers could intensify chaotic mixing of fluid and regulate the fractal dimension of flow field structure. The streamline of fluid stirred by flexible RDT-6 impeller had quasi-periodic attractors with fractal dimension of 1.9337

while the fractal dimension of chaotic attractor was 1.9545 with flexible PBT-6 impeller. It suggests that the flexible impeller could regulate multi-scale structure of the flow field by changing streamline attractor to intensify the chaotic mixing and achieve energy efficient operation.