Formation mechanisms of a dust-removal air curtain in a fully-mechanized excavation face and an analysis of its dust-removal performances based on CFD and DEM

Abstract

A high concentration of dust in a fully-mechanized excavation face is a serious threat to the safety of production underground and miners’ health. This paper discusses the use of a novel air curtain generator and proposes a novel dust control and prevention technique. Based on the k-ε two-equation turbulence model, Hertz-Mindlin model and the CFD-DEM coupled interface compiled with C++ language, this paper firstly constructs a simulation model of the coupling between airflows and dust in a fully-mechanized excavation face, and then simulates the airflow fields and dust fields under forced/exhaust ventilation conditions with and without a novel air curtain generator being utilized. The results show that when only the forced/exhaust ventilation was used, a high concentration of dust spread throughout the entire tunnel space and no effective air curtain was formed. Furthermore, after the air curtain generator was turned on, as the radial-to-axial forced air ratio (PFQ) increased, the horizontal vortex in the front of the head-on section weakened gradually, and the originally disordered airflows behind the heading machine moved uniformly towards the head-on section. As the PFQ further increased, the distance (d) between the formed air curtain and head-on section decreased overall; through a curve fitting, this relationship can be written as: d=−5.247ln(PFQ)+13.569. When the PFQ>5:5, the average negative-pressure-induced dust-exhaust capacity increased, the distance between the formed air curtain and the head-on section decreased, and the re-entrainment of dust did not take place in a straightforward manner. Finally, some field measurements were carried out in order to validate the simulated results, with the subsequent comparison showing that the numerical simulated results were basically accurate.