Study on the spatiotemporal evolution of multiphysical parameters in the flow field during coal and gas outburst disasters: New insights into the dynamic disaster-causing and thermal responses of gas-solid two-phase flow

Investigating the dynamic disaster-causing mechanism and thermodynamic response laws of gas-solid two-phase flow (GS-TPF) in coal and gas outburst (CGO) is of great theoretical guiding significance for enhancing the disaster prevention and mitigation capacity of coal mine outburst accidents. Using a self-developed experimental system for outburst dynamic disasters, we conducted comparative experiments were conducted under gas outburst (GO) and CGO conditions. The spatiotemporal evolution patterns of key characteristic parameters of the GS-TPF, including impact force, static pressure and temperature, were systematically revealed, and the differential evolution characteristics of gas-solid two-phase flow-induced dynamic disasters as well as the underlying thermodynamic response mechanism were elucidated. The results indicate that the impact force-induced disaster follows a spatial stratification mode: solid-phase-dominated impulsive behavior in the near-field zone, oscillatory alternation at intermediate distances, and sharp growth of gas-phase fluctuations in the far-field zone. In the area adjacent to the outburst outlet, the peak solid-phase impact force is approximately 2.7 times that of the gas phase. Pulverized coal reduces the local sound velocity and raises the choking probability, resulting in more disordered static pressure evolution in CGO compared with GO; the peak static pressure of GO is about 1.90 times that of CGO. The temperature exhibits a trend of initial decrease followed by increase, and the temperature drop magnitude of gas outbursts is 2.8–4 times that of CGO. Heat absorption caused by the expansion work of free gas serves as the dominant controlling factor in the cooling stage, while heat generation from the collision and friction of pulverized coal acts as the dominant mechanism in the heating stage, with its temperature homogenization capability far exceeding that of ambient heat exchange. Pulverized coal is not merely a passive migration medium; it also reshapes the energy balance structure of the flow field through the conversion of kinetic energy into thermal energy. The findings of this study can provide a theoretical foundation for the zoned prevention and control of outburst disasters and emergency rescue operations.