Abstract Summary (Max 250 words)
For the first time, experimental and numerical simulation was conducted on the mass‑transfer and key hydrodynamic characteristics of a novel type of impellers – centrifugal‑pulsed impellers (CPI) in a single and double configurations within a stirred‑tank reactor (STR). CPI generate pulsations due to the specific geometry of their surface, transforming rotational forces into local pressure pulsations. These pulses form a dynamic velocity field dependent on both amplitude and frequency, which are governed by the design features of the impeller’s curved‑shape surface and its rotational speed. This leads to reduced energy dispersion through a decrease in large‑scale turbulence within the vessel, an increase in droplet and bubble dispersion extension, improved mixing quality within the dispersed phase (especially inside droplets), and increased kinetic coefficients (i.e., heat and mass transfer). These improvements are achieved by means of localized, predominantly near‑impeller, directed energy input and reduced axial load on the impeller shaft. The pulsation mechanism was broken down through mass‑transfer coefficients and hydrophone power spectral density decomposition into key blade‑passing frequencies and their harmonics. The power number was experimentally determined, and twenty‑six configurations of impeller modifications were examined through computational modelling. Mass‑transfer coefficients, velocity fields, and specific energy‑dissipation profiles were evaluated for each CPI design, including blades with sin‑phased and counter‑phased double‑impeller configurations. It has been revealed that orifices in the impellers significantly increase local turbulence in the regions below and above the impellers by generating additional directed flows, leading to enhanced circulation throughout the entire STR volume.
