Numerical analysis of blade height ratio effects on mixing efficiency and energy consumption in triple-blade concentric double-helix static mixers

This work aims to find the optimum value of blade height ratio (R) for improving mixing performance and energy consumption of a Triple-Blade Concentric Double-Helix Static Mixer. In this study, mixing of two fluids at different concentrations subjected to laminar flow conditions is numerically analyzed by using finite element-based Computational Fluid Dynamics simulations. Different values of the R parameter are considered in a wide range of Reynolds numbers (Re = 200–1000). This analysis then carried out an in-depth study of R's effect on mixing performance, strength segregation, mixing index, helicity, velocity profile, pressure drop, pumping power, and efficiency. The findings showed that a blade height ratio of R = 2/3 gave the highest mixing index (MI), with the maximum value of 0.99 at a Re number of 600, which showed the best mixing performance in the channel. Helicity visualization also showed complex helicity patterns with increased vortex interactions for the 2/3 configuration. This geometry gave an improvement in MI by about 17.85% over Triple-Blade Concentric Single-Helix Static Mixer (TB-CSH-SM) with R = 0 at Re = 600. It is also important to mention that increasing the R value leads to an increase in pressure drop and, consequently, an increase in pumping energy consumption. Although R = 2/3 gives the best mixing performance, the energy consumption is relatively higher than that for R = 0, which has the lowest power input but a lower MI. The investigation concludes that R = 2/3 represents a balanced solution since it realizes an optimum mixing performance with a moderate energy consumption and hence is suitable for applications requiring an efficient compromise between mixing quality and energy consumption.