Selection of the auxiliary fans and their positioning in underground coal mine must be in compliance with safety requirements. Secondarily installed fan changes local pressure distribution thus generating two areas: decreased and increased pressure zones. In pressurized zone, a part of overall mass-flow goes out from working area, whereas in depression zone additional flow comes from boundaries. Total pressure changes affected by auxiliary fans are difficult to measure, but even in case of small differences, influence may be significant. Since auxiliary fans are mostly installed in new and active areas, risk from excessive harmful gasses concentrations and uncontrolled gas flow is higher then in most other areas. Computational fluid dynamic method is used for simulation of the local pressure changes. Model has been tested in working environment. Initial settings and boundary conditions for simulation are controlled and compared with experimental results. Guidelines for installation procedure and protective measures are derived based on variations of the parameters.
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