Analysis of the State of Dust-Gas-Air Mixtures in the Atmosphere of Mine Workings in the Vicinity of Spontaneous Heating Points


Annotation:

Stationary process of dusty-gas mixtures flow in the mine workings in the presence of the heat supply zone caused by spontaneous heating centers located near the workings is considered in the article. Based on the laws of conservation of mass, impulse and energy the formulas are obtained for determining the number of characteristics (speed, density, pressure, temperature, Mach number) of the dust-gas-air mixture flow, which describe the intensity of the moving front of the dust-gas-air mixture, which crossing the zone of influence of the spontaneous heating points. These expressions contain the plus or minus sign in front of the radical, so each sought function has two significantly different meanings.

The problem is formulated on the influence of the thermal field caused by the points of spontaneous heating on the flow of dust-gas-air mixtures in the room. It was identified that for any Damkeler number representing the dimensionless amount of heat input, each of the functions found, that characterizes the stationary flow of mixtures along the working, consists of two sections. Their boundaries are two critical Mach numbers, and, moreover, the flow of mixtures in the section between them is unsteady. The larger the Damkeler number is, the longer is the section between the critical Mach numbers, and the more unsteady nature of the dust-gas mixture flow is manifested.

The conditions for the unsteady flow of mixtures are revealed. Plots are constructed that characterize the changes in the parameters of dust-gas-air mixtures crossing the zone of influence of spontaneous heating points. At critical values of heat input, the relative values of pressure and density of mixture increase monotonically with increasing the critical Mach numbers. With a Mach number equal to one, the Damkeler number assumes zero value. This indicates the impossibility of supplying heat to the dust-gas mixture when it moves in a stationary mode.

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DOI: 10.24000/0409-2961-2019-9-15-21
Year: 2019
Issue num: September
Keywords : Mach number mine workings enthalpy dust-gas-air mixtures spontaneous heating points the law of conservation of mass the law of conservation of momentum the law of conservation of energy Damkeler number compression shock wave
Authors:
  • Cherdantsev S.V.
    Cherdantsev S.V.
    Dr. Sci. (Eng.), Chief Research Associate, svch01@yandex.ru AO «Scientific Research Center VostNII on Safety of Work in the Mining Industry», Kemerovo, Russia
  • Shlapakov P.A.
    Shlapakov P.A.
    Cand. Sci. (Eng.), Laboratory Head AO «Scientific Research Center VostNII on Safety of Work in the Mining Industry», Kemerovo, Russia