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

摘要

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-epsilon 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 (P-FQ) 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 P-FQ 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 = -5.247 ln(P-FQ) + 13.569. When the P-FQ > 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. (C) 2017 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.