Research on multi-radial swirling flow for optimal control of dust dispersion and pollution at a fully mechanized tunnelling face

In order to control the high-concentration dust pollution and protect the health of workers at a fully mechanized tunnelling face, numerical simulation on multi-radial swirling flow is performed to control the migration of dust produced by the excavation at a fully mechanized tunnelling face. The result shows that the airflow is in turbulent regime in the fully mechanized rock tunnel with far-pressing-near-absorption (FPNA) ventilation. An evident swirling flow field exists behind the dedusting fan, and the dust produced by the tunnelling face migrates to the entire tunnel. It is difficult to control the dust pollution through single FPNA ventilation. The field test shows that the simulation result is generally accurate. The dust migrates over a shorter distance L-D (the distance of dust migration) when the distance between where the multi-radial swirling flow is generated and the tunnelling face, i.e., L-G (the distance between multi-radial swirling flow generator and tunnelling face) is relatively long. For L-G = 20 m, the multi-radial swirling flow field produced by generator is converted into an effective dust-control air curtain where the tunneller driver is located, and the dust is controlled in front of the driver. For L-G > 20 m, L-D changes slightly and becomes stable. For Q(p) (the pressurized air volume) = 200 m(3)/min and Q(p) >= 450 m(3)/min, the dust migrates behind the tunneller driver, and the optimal Q(p) is between 230 m(3)/min and 400 m(3)/min.