Analysis and Optimization of Kenics Static Mixers

Authors:

O. S. Galaktionov

P. D. Anderson

G. W. M. Peters

H. E. H. Meijer 

This paper utilizes the mapping approach to analyze and optimize the distributive mixing performance of Kenics static mixers, facilitating the efficient comparison of thousands of different layouts. The study specifically investigates the impact of varying blade twist angles within two primary design configurations: conventional alternating twist directions (RL) and constant twist directions (RR).



By simulating Stokes flow and decomposing the mixer into functional modules, the analysis identifies optimal geometries for maximizing macroscopic homogenization and interface generation.

Key Learnings

• Mapping Method Efficiency: The use of the mapping technique allows for the evaluation of thousands of mixer layouts without the prohibitive computational cost of recalculating full 3D velocity fields for every design variation.
• Optimal Blade Twist: Research suggests that the "standard" 180° twist may not be the most efficient for homogenization; a 120° twist (RL-120) is often more energy-efficient and provides better material stretching.
• Design Configurations (RL vs. RR): The study identifies two primary layouts—RL (alternating Right-Left twist directions) and RR (constant Right-Right twist direction)—noting that RL is generally superior for creating the "Baker's Transformation" effect.
• Baker’s Transformation Mimicry: The mixer operates by repeatedly cutting, reorienting, and stacking material, roughly doubling the number of striations with each successive mixing element.
• Flow Characteristics: Under common industrial conditions, the mixer operates in Stokes flow (low Reynolds numbers), where inertial forces are negligible and mixing is purely distributive.
• Transition Zones: The velocity field is significantly disturbed at the junctions between blades; the study defines these transition zones as spanning approximately a 45° turn of the blade.