Experimental study on migration attenuation law of two-phase flow in coal and gas outburst

Abstract

In order to study the migration and attenuation law of coal and gas two-phase flow after coal and gas outburst, the characteristics of migration and separation of pulverized coal after outburst and the evolution law of impact pressure of coal and gas two-phase flow were studied by using the self-built experimental simulation system of coal and gas outburst. The results show that the relative outburst strength of pulverized coal is 55.1% when the axial stress is 0.54 MPa and the gas pressure is 0.5 MPa. The distribution of pulverized coal with particle size less than 1 mm shows a decreasing trend along the pipeline, while the distribution of pulverized coal with particle size 1-3 mm and larger than 1 mm shows an increasing trend along the pipeline. After the outburst starts, the impact pressure of two-phase flow increases first and then decreases, and the increase rate is greater than the decrease rate. The peak time of the impact pressure lags with the increase of the outburst distance. Due to the instantaneous outburst, the two-phase flow rapidly spits out from the state of incomplete expansion into the state of complete expansion, resulting in layer upon layer compression waves and finally forming shock waves, resulting in a sudden increase in the peak impact pressure in the front section of the pipeline, and the overall trend of oscillation attenuation.

Keywords

• coal and gas outburst
• two-phase flow
• separation characteristic
• impact pressure
• attenuation law