Effect of meso/micro multiple scale turbulent shear mixing on the synthesis process of micro/nano oxide particles in continuous multistage Rankine vortex flow

• Multiscale modelling of intensified turbulence shear controllable synthesis of micro/nano SiO 2 particles. • CFD/DPM analysis conducted for the effect of mesoscale/microscale turbulent eddies on the synthesis of SiO 2 nano-particles. • The application of SVFR reactor can effectively intensify the local turbulence shear. • Turbulence shear is crucial for SiO 2 nanoparticle synthesis size and morphology control. An Eulerian Computational Fluid Dynamics modelling coupled with the use of Lagrangian Discrete Phase Model (CFD/DPM) was employed to investigate the effect of meso/micro multiple-scale turbulent mixing on the synthesis process of micro/nano oxide particles in a continuous multistage Rankine vortex flow. The changes from micro- to macro-scale interactions among different scales, including the coupling of particle entrainment by turbulent eddies and synthesis reaction in the Rankine vortex flow and the mesoscale structure (i.e., particle aggregates and reactor scales) were systematically studied, especially focusing on the influence of meso/micro scale turbulent eddies on the synthesized micro/nano particles. It has been demonstrated that the use of Eulerian-Lagrangian framework (CFD/DPM) can effectively capture the simultaneous interactions between aggregated particles and turbulent eddies, enabling the evaluation of how operational variations, specifically in the eddy size based Reynolds number and reactant concentration, to affect the final particle properties. Numerical results for a range of these conditions have shown a strong agreement with the experimental data. The present study has demonstrated that the multistage Rankine vortex flow can effectively intensify the local turbulence induced shear at meso/micro scales, thereby controlling nanoparticle aggregation and breakage to facilitate the production of uniform, meso -sized particles with well-defined morphology.