Improvement on the distribution uniformity of hydrodynamics in a stirred tank with an H-like fractal impeller

doi:10.1016/j.cjche.2025.01.004

Abstract

Abstract: Fractal theory provides a new strategy for equipment design. In this work, we propose a novel H-like fractal (HLF) impeller to improve the uniformity of the distribution of hydrodynamics in stirred tanks. The impellers are constructed by replacing two vertical blades or four legs with two or four H-like sub-blades by fractal iterations, respectively. Flow characteristics including velocity and turbulent kinetic energy (TKE) distributions, vortices, power number, are predicted by large eddy simulation. Compared with Rushton turbine (RT) impeller when H/T = 1 (or dual RTs when H/T = 1.5, triple RTs when H/T = 2), the HLF impeller can produce a flow field with more uniform distributions of larger velocities and TKE level. The impeller with more fractal iteration times can further improve the distribution uniformity of hydrodynamics in the case of high H/T. Power analysis shows that this is mainly due to the improved energy utilization efficiency by the fractal structure design.

Key words: Fractal, Impeller, Mixing, Stirred tank, Large eddy simulation (LES)

摘要： Fractal theory provides a new strategy for equipment design. In this work, we propose a novel H-like fractal (HLF) impeller to improve the uniformity of the distribution of hydrodynamics in stirred tanks. The impellers are constructed by replacing two vertical blades or four legs with two or four H-like sub-blades by fractal iterations, respectively. Flow characteristics including velocity and turbulent kinetic energy (TKE) distributions, vortices, power number, are predicted by large eddy simulation. Compared with Rushton turbine (RT) impeller when H/T = 1 (or dual RTs when H/T = 1.5, triple RTs when H/T = 2), the HLF impeller can produce a flow field with more uniform distributions of larger velocities and TKE level. The impeller with more fractal iteration times can further improve the distribution uniformity of hydrodynamics in the case of high H/T. Power analysis shows that this is mainly due to the improved energy utilization efficiency by the fractal structure design.

关键词: Fractal, Impeller, Mixing, Stirred tank, Large eddy simulation (LES)

Hui Li, Pan You, Xiaoyang Chen, Huiming Yang, Peicheng Luo. Improvement on the distribution uniformity of hydrodynamics in a stirred tank with an H-like fractal impeller[J]. Chinese Journal of Chemical Engineering, 2025, 82(6): 83-94.

Hui Li, Pan You, Xiaoyang Chen, Huiming Yang, Peicheng Luo. Improvement on the distribution uniformity of hydrodynamics in a stirred tank with an H-like fractal impeller[J]. 中国化学工程学报, 2025, 82(6): 83-94.

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