Impact of multi-component evaporation on turbulent spray combustion investigated by Direct Numerical Simulation

Spray flame synthesis (SFS) is a widely used technique for producing nanoparticles. To optimize corresponding applications, an accurate prediction of flame behavior and precursor distribution is crucial. This study investigates the influence of evaporation on spray flame dynamics by comparing single-component and multi-component evaporation models in direct numerical simulations (DNS) of ethanol sprays containing titanium isopropoxide (TTIP) as precursor under reactive conditions. Simulations are conducted using different TTIP concentrations to assess the sensitivity of evaporation rates, droplet lifetimes, flame structure, and precursor distribution. Results reveal that the multi-component evaporation model leads to slower droplet evaporation, larger droplet diameters, and a thinner flame located closer to the central axis of the jet compared to the simplified, single-component model. In contrast, the single-component model overestimates the evaporation rate (based solely on ethanol properties), resulting in broader flame zones. Scatter plots and time-averaged fields show significant discrepancies in the gas-phase concentrations of ethanol and TTIP between the two models. These differences have important implications for nanoparticle synthesis, where precursor distribution affects particle growth and morphology. These findings emphasize the importance of multi-component evaporation models for accurate simulations of spray flames involving complex liquid mixtures.