A Multiscale Simulation and Experimental Study on the Microfog Evolution and Dust Control Mechanism Driven by Ultrasonic Atomization

To address coal dust pollution arising during belt transportation in open-pit coal mine preparation plants, this study systematically elucidates the evolutionary dynamics of microdroplets and their dust suppression mechanisms under ultrasonic atomization. First, a theoretical analysis clarified the fundamental principles and dominant factors governing ultrasonic atomization. Subsequently, a combination of macroscopic spray experiments and microscopic numerical simulations was employed to investigate the coupled effects of gas pressure <i>P</i> _g and liquid pressure <i>P</i> _l on the gas-liquid flow ratio <i>Q</i> _l/<i>Q</i> _g and droplet velocity <i>v</i>. Power-law correlations were established as <i>Q</i> _l/<i>Q</i> _g = 6.16-(<i>P</i> _l/<i>P</i> _g)^-1.4 and <i>v</i> = 0.176-(<i>P</i> _l/<i>P</i> _g)^-0.067. Results indicate that the droplet concentration exhibits a radially symmetric unimodal distribution and decays monotonically along the axial direction. The dust suppression efficiency was found to be positively correlated to the airflow rate, particle size, and effective action distance. For near-field rapid capture of respirable dust, operating conditions with "high gas pressure-medium-to-low liquid pressure" (<i>P</i> _g ≥ 0.6 MPa, <i>P</i> _l = 0.1-0.3 MPa) were optimal, whereas for surface wetting and areal coverage scenarios, moderately elevated liquid pressure (<i>P</i> _l = 0.4-0.5 MPa) combined with medium gas pressure (<i>P</i> _g = 0.30-0.45 MPa) proved more favorable. Field applications demonstrated that under optimal conditions, the swirling ultrasonic atomizer achieved dust suppression efficiencies of approximately 80% for total dust and 75% for respirable dust. This research unveils the multiscale mechanisms of ultrasonic atomization for dust control and provides both theoretical insight and practical guidance for developing low-water, high-efficiency dust mitigation technologies in mining operations.