Prediction of Dynamic Wetting and Encapsulation Mechanisms between Microdroplets and Rough Coal Dust Particles

Coal dust poses a severe threat to workers’ health, frequently causes accidents, and leads to pneumoconiosis. As the mainstream method of dust suppression, wet spraying has attracted considerable attention due to its efficiency. Understanding the dynamic wetting and encapsulation mechanisms between fog droplets and coal dust particles is crucial for optimizing fine water mist removal technology, especially for removing respirable coal dust smaller than 7 μm. However, studies on the adhesion behavior of droplets impacting rough coal dust at the microscopic scale are insufficient. Therefore, we adopted the numerical simulation method of CLSVOF and dynamic mesh to deeply analyze the collision behavior between droplets and rough coal dust at the micrometer scale from the perspectives of impact velocity, particle size ratio, and roughness. The research indicated that when θ ≥ 1, FMES droplets at V = 20 m/s and AEO9 droplets at V = 30 m/s can effectively encapsulate and wet the coal dust, with wetting areas of A = 0.98 and A = 0.99, respectively. Furthermore, we explored the correlation between V and θ and established optimal wetting discriminant formulas and rebound-encapsulation critical equations. Moreover, the greater the rough protrusions on the surface of coal dust, the greater the retention of the initial gas film. The studies provide theoretical guidance for optimizing spray conditions, enhancing the wet dust removal process with optimal parameter ranges for practical use. They also have significant implications for the development of droplet impact research.