Network Model of Air Distribution in Face Areas of Blind Headings
M. A. Semin, G. Z. Fainburg, S. V. Mal’tsev
Mining Institute, Ural Branch, Russian Academy of Sciences, Perm, Russia
seminma@inbox.ru
Keywords: Blind headings, face area, blowing ventilation, network model, ideal displacement model, flow-oriented model
Abstract
The authors discuss the problem of correct description of blind heading ventilation within the framework of the classical network-based approach to calculation of air distribution in mines. Voronin’s formula based on the assumed ideal agitation omits the spatial structure of air flow in a face zone and neglects the terminal time of flow circulation in large-scale vortex. A network model of blind heading ventilation is proposed with regard to air circulation in a face area owing to inertia of air flow from ventilation duct, and to its interaction with return air. In the conventional approach, a branch of a graph is collated with a heading, while in the proposed approach, it conforms with an individual air flow. The flow-oriented model is compatible with the classical network approach and can be integrated in computational modules of problem solving in mine ventilation. The model was used to obtain a theoretical explanation for the phenomenon of excess of the total circulating air flow rate in a face area of a blind heading over the air flow rate from a ventilation duct. It is found that vortex recirculation of air does not define the rate of removal of harmful impurities; however, in complicated structure flows, dynamics of a decrease in concentration of impurities is governed by the duration of air flow circulation in different circulation loops. Inhibition of ventilation in face areas is connected with the presence of low-velocity and remote areas in vortex; inclusion of these areas in consideration allows explaining deviations due to removal of impurities within the framework of the ideal displacement model.
|
