A novel invisible air curtain technique for efficient dust suppression in heading excavation

To address high-concentration dust pollution at the excavation face, this study proposes an intelligent ventilation system featuring an invisible air curtain. Based on the collaborative mechanism of jet flow and air curtain, coupled with CFD simulation, field measurement, and similarity experiments, this study systematically analyzes the influences of the axial-to-radial air volume ratio and pressure air volume on dust migration characteristics. The results show that an excessively low axial air proportion fails to form a dominant jet in the heading area, and radial airflow disturbs the flow field, causing dust to spread toward the rear of the roadway. Insufficient pressure air volume makes it difficult to establish a stable jet and an invisible air curtain. Conversely, an excessive air supply increases turbulent kinetic energy and leads to disordered airflow within the roadway. When the axial-to-radial air volume ratio is 5:5, and the total air volume is 600 m3/min, the system realizes high-efficiency dust control and energy conservation. Under these conditions, the axial jet forms a stable vortex field at the heading face that effectively captures dust, while the radial air curtain blocks dust diffusion toward the roadway rear. The average dust concentration at the driver's position is 0.68 mg/m3, corresponding to a dust reduction of more than 98% in the main working zone compared with traditional ventilation. This study clarifies the synergistic mechanism of vortex confinement and air curtain isolation, providing a technical reference for high-efficiency dust control and energy-conserving ventilation design in coal mining.