Research on atomization characteristics and dust suppression performance of a new negative-pressure spraying device

To address the issue of dust dispersion in fully mechanized mining faces, a novel negative pressure-spraying dust suppression device based on the principle of the Coanda effect was designed. This device not only effectively covers the dust generated by the shearer drum but also utilizes the suction effect generated by the device itself to collect the dispersed dust in the tunnel. Computational fluid dynamics (CFD) was used to conduct numerical analysis of the airflow field and droplet characteristics in the shearer working face. An orthogonal experiment was performed to investigate the effects of nozzle aperture (A), spraying pressure (B), installation angle (C), and negative pressure device pressure (D) on the atomization characteristics and suction effect of the device. The results indicate that the importance order of the factors influencing droplet size is B > D > C > A, and the importance order of the factors influencing suction velocity is D > C > B > A. As the spraying pressure increases, the droplet size distribution becomes increasingly concentrated, which promotes droplet refinement. For droplet mass concentration, a larger nozzle aperture helps form a higher mass concentration droplet field, while spraying pressure has a minimal effect on droplet mass concentration. The pressure of the negative pressure device significantly affects droplet velocity; as the negative pressure device pressure increases, the droplet velocity increases, while changes in spraying pressure have little effect on droplet velocity. Comprehensive analysis revealed that the optimal parameter combination for droplet size distribution, droplet velocity, and dust suppression performance is: nozzle aperture (A) of 2.4 mm, spraying pressure (B) of 8 MPa, installation angle (C) of 0°, and negative pressure device pressure (D) of 0.2 MPa. Under these conditions, the suction airflow can reach 360 m³/min, and the device achieves optimal dust suppression performance. A comparison of the effectiveness of dust suppression device before and after its application on the shearer shows that the device not only effectively encapsulates the dust source from the drum but also guides the airflow in the tunnel, reducing the diffusion of dust into the working area.