Investigation of Aerodynamic Parameters of Underground Mine Ventilation Using Fan-ejector Units

This article investigates the determination and evaluation of the aerodynamic parameters of a mine ventilation network when fan-ejector units are used for the ventilation of underground mine workings. Dead-end workings of the Zarmitan and Gujumsay mines of JSC “NMMC”, characterized by complex ventilation conditions, were selected as the research objects. The mining and technical conditions of the mines, the total power of self-propelled mining equipment, the required standard airflow rate, and the air capacity of the installed VM-6 auxiliary ventilation fan were comparatively analyzed. The calculations showed that the required airflow exceeds the fan capacity by a factor of 1.72 times at the Zarmitan mine and 1.06 times at the Gujumsay mine. The aerodynamic resistance of the ventilation network was evaluated on the basis of airflow rate and pressure loss, and the quadratic relationship between mine depression and airflow rate was analyzed. When the fan-ejector unit was incorporated into the ventilation network, airflow distribution was investigated using Kirchhoff’s first and second laws, taking into account the airflow balance at network junctions and the pressure balance within closed ventilation circuits. For the iterative ventilation-network calculations, a numerical tolerance of ΔQ/Q₀ ≤ 5% was adopted in this study as the convergence criterion for the airflow balance. In addition, the pressure characteristic of the fan-ejector unit was evaluated from the difference between the total pressures at its inlet and outlet, while its relative efficiency was analyzed as a function of the mixed airflow rate. The obtained results demonstrate that the operating mode of a fan-ejector unit should be determined through an integrated consideration of airflow rate, aerodynamic resistance, mine depression, airflow distribution within the ventilation network, and the pressure characteristics of the unit. The results can be used to substantiate the operating parameters of fan-ejector units and to evaluate the aerodynamic performance of auxiliary ventilation systems in underground mine workings with complex ventilation conditions.