Specifics of the Shock Front Formation at the Sections of Turns of the Mine Workings


It is established that the development of coal deposits, especially on deep horizons, is usually accompanied by gas-dynamic and thermophysical processes. These are dangerous phenomena that initiate detonation and shock waves, which lead to especially serious accidents. The system of workings at the mining enterprises has a complicated branched structure with numerous turns, branches and junctions. Gas-air flows do not always move in a straight line, at the curved sections they turn around, and, also branch out, moving from one working to another. As a result, the process of the shock front formation changes significantly, since the normal line to it does not coincide with the direction of the gas-air flow velocity, as it takes place in the straight mine workings.

The specific features of the shock front formation in the gas-air mixtures at the sections of the mine workings turns are considered in the article. For specific parameters of the gas-air mixture, when the working is turning to the preset angle, the shock polar is built. With its help, the gas-dynamic and thermophysical characteristics are determined, and some regularities of the gas-air flow movement behind the shock front are identified. It is determined that at any fixed Mach number, the pressure, density and temperature behind the shock front when the working is turning is always less than the similar characteristics behind the shock front at the straight section. With an increase in the Mach number, the pressure, temperature, and density are increasing monotonously, moreover, the pressure plots are in the form of the concave curves, and the plots of temperature and density are almost straight lines. The conditions for the formation of the detached shock wave at the edge of the wedge in the mine workings junctions are noted.

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DOI: 10.24000/0409-2961-2020-5-29-35
Year: 2020
Issue num: May
Keywords : Mach number mine workings gas-air mixtures shock wave front critical speed shock polar Bernoulli equation