Research progress on the two-phase flow migration law of coal and gas outburst

Coal and gas outburst is an extremely complex dynamic phenomenon in coal mines. It is mainly manifested as gas suffocation, pulverized coal impact and burial, which seriously threatens the safety production of coal mines. Revealing the migration law and its main controlling factors of two-phase flow in coal and gas outburst is of great significance for clarifying the disaster-causing mechanism of outburst and guiding disaster prevention and avoidance on site. In recent years, relevant scholars had carried out a large number of coal and gas outburst two-phase flow test and theoretical research, and had achieved fruitful research results. This paper summarized and analyzed the two-phase flow simulation test device and the research results obtained by domestic and foreign scholars in the two-phase flow field. Firstly, the existing two-phase flow physical simulation test devices for coal and gas outburst were systematically reviewed, and the key parameters and functional advantages of different test devices were compared and analyzed. On this basis, the migration velocity, migration pattern and accumulation distribution characteristics of outburst pulverized coal flow, as well as the formation reason, propagation velocity and attenuation law of outburst shock wave were summarized. Finally, the influence and control effect of roadway structure, gas pressure, coal particle size, ground stress and gas composition on outburst two-phase flow were analyzed. According to the analysis, the research on the two-phase flow of coal and gas outburst at the present stage shown the characteristics of visualization of outburst process, complexity of roadway structure, diversification of data collection, comprehensiveness of influencing factors and diversification of research methods, and basically grasped the occurrence mechanism, propagation and disaster-causing law of outburst two-phase flow. However, the establishment and improvement of similarity system (similarity criteria and materials), the coexistence and mutual interference principle of two-phase flow and ventilation system, the multi-factor coupling disaster-causing mechanism of two-phase flow, and the integration of disaster-causing and prevention and control of two-phase flow still need further in-depth study.