Based on the characteristics of structure and operation of coaxial mixer

a three dimensional mathematical model considering the flow and mixing process was developed.A novel coaxial mixer consisting of different combined inner impellers with upper and lower blades and outer wall-scraping frame was simulated and its power consumption

flow field and mixing characteristics in a highly viscous Newtonian fluid under co-rotating and counter-rotating modes were obtained.The results show that the total power consumption is less and the mixing efficiency is higher under co-rotating mode.The power consumption of outer impeller is largely influenced by combined inner impeller

which decreases with the increase of speed of inner impeller under co-rotating mode and increases under counter-rotating mode.For the combined inner impeller composed of turbine paddles

the specific volumetric mixing energy with the same Reynolds number is less when the diameter ratio between the inner impeller and stirred vessel is about 0.35.For highly viscous Newtonian fluids

the coaxial mixer with combined inner impeller with upper two-pitched-blade turbine and lower two-straight-blade turbine is better only when the Reynolds number in the mixing system is below 36; otherwise

the combined inner impeller with upper six-pitched-blade turbine and lower six-straight-blade turbine consumes less energy.