Effect of surface roughness of solid particles on the regimes and outcomes of their collisions with liquid droplets

The paper presents the experimental research findings for the characteristics of the collisions of liquid droplets with solid particles (as illustrated by distilled water and metal particles) with a variable average roughness. The average roughness range (0.05–39 µm) corresponded to a group of practical applications: heat exchange, treatment, evaporation, fuel systems, etc. The regimes of droplet-particle collisions, as well as the characteristics of secondary liquid fragments, i.e., child droplets, were determined. Interaction regime maps for droplets and particles were constructed. Mathematical equations to describe the boundaries of droplet-particle interaction regimes were obtained. The findings were compared with the characteristics of collisions of liquid droplets with a flat solid substrate made of the same material as the particles with equivalent average roughness. Guidelines were provided for applying the research findings to the development of the technologies of secondary atomization of liquid droplets in applications.