Simulation experiments on the controllability of dust diffusion by means of multi-radial vortex airflow

In order to control the diffusion of dusts towards the working area in an excavation face, a novel multiradial vortex wind generator was designed and developed in this study. Using a self-designed simulation system, the multi-radial vortex airflow migration and dust diffusion rules were experimentally investigated. As to the airflow migration, it was easier to form the dust suppression air curtains with uniform airflow distribution at a longer distance away from the head-on section (L-vortex), under smaller forced-to-exhaust ratio (Y), forced air flow rate (Q(forced)) and axial-to-radial-ratio (Z), with the airflow pointing to the head-on section. As to the control of dust diffusion, the dust concentration decreased gradually with the increase of L-section. As the distance away from the head-on section increased, the control capacity of dust diffusion firstly weakened and then strengthened. The smaller values of forced-to-exhaust ratio and axial-to-radial ratio and the larger forced air flow rate would be beneficial to the control of dust diffusion. When the ventilation parameters were reasonably set, the airflow distribution of the dust suppression air curtain, the airflow direction and the hindrance on dust diffusion tended to be stable. Additionally, the optimal ventilation parameters were determined in this study, i.e., L-vortex = 20 m, Y = 5: 4, Q(forced) = 200 m(3)/min and Z = 1: 9. Under the optimal condition, the average removal ratios of total dusts and respirable dusts were as high as 96.02% and 95.51%, respectively. (C) 2018 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.