Spreading Dynamics of Binary Solution Droplets on Heated Curved Surfaces: Experiments and Numerical Simulations

Efficient thermal management is critical for high-power electronic devices, and droplet impact boiling has emerged as a highly efficient cooling method because of its exceptional heat transfer capability driven by phase change dynamics. The alcohol droplet impacts on curved surfaces are crucial for optimizing spray cooling and surface coating, as well as for understanding multiphase flow interfaces. This study focuses on binary solution droplets composed of water and ethanol with low-concentration glycerol added as an additive. Experiments and numerical simulations analyze the impact behavior dynamics and heat transfer mechanisms of the droplets, which are influenced by the surface morphology, wettability, temperature, and impact height. Research indicates that the convex surface exhibits a combined advantage over the flat and concave surfaces in promoting droplet spreading and a concentrated rebound pattern. The hydrophobic convex surface suppresses droplet spreading and facilitates the bouncing. The synergistic interaction between the convex surface and temperature intensifies droplet heat transfer and phase transition processes, yielding five distinct impact regimes. A higher Weber number correlates with greater droplet spreading, faster morphological changes, higher bouncing heights, and shorter rebound onset times. Concurrently, the synergistic effect of surface temperature and Weber number determines the intensity of the droplet morphological transformations. Binary solution droplets with high glycerol concentrations exhibit more pronounced suppression of spreading, while their morphological changes and degrees of breakup after impact with the heated convex surface are significantly exacerbated. For binary solution droplets with varying glycerol concentrations, differences in the coupled effects of the droplet's thermophysical properties significantly influence their tendency toward fragmentation.