Mechanism of the Influence of Design Parameters on the Power Characteristics of a Multi-Stage Cup-Shaped Paddle Agitator Based on CFD Simulation

Agitator reactors are widely used in chemical production processes, and their structural design has a significant impact on power consumption. Therefore, this study performs numerical simulations of multi-stage cup-shaped paddle agitators with different geometric parameters, and discusses in detail the effects of the paddle spacing (S/H), the ratio of the upper paddle length to the reactor radius (Ls/R), the ratio of the lower paddle length to the reactor radius (Lx/R), and the ratio of the upper to lower paddle lengths (Ls/Lx) on the reactor’s power characteristics and internal flow field. Equations were derived to relate the power number (Np) to parameters such as Re, Ls/R, and Lx/R. The study found that, at the same Reynolds number, torque exhibits a slight upward trend as the paddle spacing increases; the best mixing effect is achieved when S/H is 0.333. Based on this pitch, when Ls/R, and Lx/R exceed 0.67, the mixing process fails to form a stable and complete radial circulation; when Ls/R and Lx/R are less than 0.53, the high-velocity zone in the flow field decreases, leading to the formation of dead zones. Therefore, selecting a multi-stage cup-shaped impeller with an Ls/R value of 0.53, an Lx/R value of 0.53, and Ls/Lx of 1 can achieve better mixing results with lower power consumption. These findings provide a reference for the energy-efficient optimization design of multi-stage cup-shaped impeller mixers in industrial applications.