Effect of air velocity on droplet generated dynamics and spray dust removal efficiency

The droplet profile is a critical factor to influence the efficiency of spray dust removal and is affected by the external environment and droplet generation condition. In this study, the process of droplet generation under airflow was investigated via the high-speed camera. The droplet generation was divided into two stages according to the symmetry of the droplet, including Balance and Oscillation. The Balance and Oscillation time both decreased with air velocity increasing, which resulted in the droplet generation time and equivalent diameter shortening in high airflow environments. The droplet's left-half width, right-half width, and width all increased with fluctuations, whereas the contact angles decreased and then increased with fluctuations during the Oscillation stage. The oscillating frequency of the droplet first decreased and then kept a constant of 15 Hz. Furthermore, three-type characteristics of droplet centroid location at the detachment were the Windward region, Symmetry axis, and Leeward region, and the probability of the Leeward region increased with air velocity, whereas the probabilities of the Windward region and Symmetry axis both decreased with increasing air velocity. These results were mainly that the dynamic pressure force increased as air velocity increased, resulting in the horizontal component of capillary force on the droplet increasing, while the decrease in the vertical component of capillary force on the droplet was the main force to resist the droplet generation. Additionally, the dust removal efficiency increased with air velocity due to the increase in specific surface with air velocity increasing. These findings offer valuable insights for advancing technology development for wet dust removal.