Blind Roadway Ventilation Improvement by Means of Increasing Initial Air Flow Velocity
B. P. Kazakov, A. V. Shalimov, O. S. Parshakov, A. V. Bogomyagkov
Mining Institute, Ural Branch, Russian Academy of Sciences, Perm, 614007 Russia
Keywords: Blind face, air jet, turbulence, diffusion, circulation, air throw, ventilation duct, Coanda effect, air jet confinment
Abstract
The test data on confined air throw ranges in dead ends are reviewed. It is found that the research findings differ greatly and disable the single-value determination of the allowable lag between the air duct and heading fact at the acceptable accuracy. It is supposed that the discrepancy of the testing data is ensues from the empirical concept of independency of the confined dead-end air throw range from the initial air flow velocity, which is strictly unproved. The supposition is backed with the numerical modeling data on blind roadway ventilation with visualization of air flow shortage at air velocities not less than 0.25 m/s. At the increased capacity of air fan and with the enhanced initial air flow velocity from 5 to 80 m/s, the air throw grows to 56 m. The authors come to a conclusion that the efficient and resource-saving approach to blind roadway ventilation is the increased air supply in air ducts, which makes it possible to extend the distance between the air duct and the face toward safe blasting.
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