Mixing Characteristics of Shear-Thinning Fluids in a Fractal Perforating Impeller Stirred Reactor

Fractal perforating impeller wasintroduced to minimizethe stagnationzone and enlarge the well-mixed zone for the mixing process of shear-thinningfluids with yield stress in a stirred reactor. The mixing performanceof the fractal perforating impeller was investigated by applying experimentalanalyses and numerical simulation. The results showed that the fractalspaces introduced in the impeller blades provided a reduction in powerconsumption and an improvement in mixing efficiency compared withstandard ones, and the mixing efficiency and the energy-saving effectcontinued to improve with the increase of the fractal iteration numberof fractal spaces in the impeller blades. The fractal-3 perforatingimpeller reduced about 27.92, 25.87, and 12.56% of power consumptioncompared with a Rushton turbine, fractal-1 perforating impeller, andfractal-2 perforating impeller at Re (y) =128, respectively. Meanwhile, the fractal-3 perforating impeller decreasedabout 22.06, 18.18, and 8.25% of the mixing time compared with a Rushtonturbine, fractal-1 perforating impeller, and fractal-2 perforatingimpeller at P (v) = 0.45 kW & BULL;m(-3), respectively. In addition, the introduction of fractal spaces inthe impeller blades could reduce the size of the trailing vortex anddestroy the recirculation zone compared with standard ones, and thishelped reduce the energy consumed at the tailing vortices and dedicatemore energy to fluid mixing. A desired result was obtained that thedesign of a fractal perforating impeller could expand the high-velocityregion and enlarge the size of the cavern compared with a Rushtonturbine and increasingly so with the increase of the fractal iterationnumber of fractal spaces in the impeller blades.