Quantitative study on gas dynamic characteristics of two-phase gas-solid flow in coal and gas outbursts

•A two-phase gas-solid flow model for outburst shock waves is established.•Three parameters of the release of gas pressure potential energy are defined according to the energy transformation during gas expansion process.•The gas dynamic characteristics of two-phase flow in the initiation stage are quantitatively studied under the four factors: initial gas pressure, particle volume fraction, particle size and outburst hole size, which is verified by experiments. The dynamic effect of coal and gas outburst seriously threatens the safety of underground equipment and workers in mines. In this paper, the models for outbursts are established, and according to the energy transformation during gas expansion process, three parameters of the release of gas pressure potential energy are defined and the gas dynamic characteristics of two-phase flow in the initiation stage are quantitatively studied under the four factors: initial gas pressure, particle volume fraction, particle size and outburst hole size. The gas dynamic characteristics in numerical simulations are verified by experiments. The results show that for the influence of the factors on the gas dynamic characteristics of two-phase flow, initial gas pressure >outburst hole size >particle volume fraction ≈particle size. The solid particles block the pressure potential energy release from chamber, so does the caliber. However, the maximum of pressure drop occurs when the caliber is 80% of the chamber, which explains the outbursts in mines are so violent due to the caliber smaller than the internal space. This paper provides a novel quantitative research method of gas dynamic characteristics of coal and gas outburst, which is of guiding significance to the design of outburst prevention facilities and emergency rescue measure.