Stability of Convective Ventilation of the Mine after Turning off the Fan
B. P. Kazakov, A. V. Shalimov
Mining Institute, Ural Branch, Russian Academy of Sciences, ul. Sibirskaya 78a, Perm, 614007 Russia
Keywords: рудник, ствол, естественная тяга, конвекция, депрессия, теплообмен, устойчивость, объемное расширение, гидростатическое сжатие, Mine, shaft, natural draft, convection, depression, heat exchange, stability, volume expansion, hydrostatic compression
Abstract
The stability of convective air motion in mine shafts after turning off the draft source was investigated. Based on numerical simulation, it was found that the mine ventilation with natural draft was violated by the formation of air vortices extended along the shaft depth. The transverse profiles of motion speed and air temperature were determined in approximation of a plane-parallel laminar flow of an incompressible medium with a vertical temperature gradient in the gravity field. Analytical calculations of the stability of the found flow to plane long-wave perturbations were carried out, as a result of which the value of critical Rayleigh parameter was obtained. A correction to the coefficient of air volume expansion was simulated, allowing to consider the hydrostatic compressibility of air. The dependence of the critical value of air temperature vertical gradient in the shaft was calculated, the excess of which leads to the formation of convective vortices and violation of through ventilation.
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