Theoretical research and control measures of gas accumulation based on airflow oscillation model in the upper ventilation of parallel roadway

In the field of coal mining, a safe and stable ventilation system is the lifeline of coal mines, and the gas flow generated after the occurrence of coal and gas protrusion disasters seriously affects the stability of the wind flow in the shafts. Therefore, it is of great significance to study disaster control and loss reduction after coal-gas outburst. Previously, there were fewer studies on airflow oscillations in open-loop systems in coal mines. Comprehensive use of theoretical analysis, experimental analysis, and numerical simulation to study the oscillatory behavior of airflow in coal mine open-loop systems. Control equations for an idealized open-loop branching system are defined, and a numerical analysis method that considers dispersion and mixing at the air-methane interface is developed and validated against a physical model. This study derives the oscillatory behavior of airflow caused by gas wind pressure in upward ventilation of parallel inclined roadways. Using modeling to parameterize the effect of initial airflow velocity of stagnant methane in upward ventilated roadways containing parallel branching roadways, the conditions for controlling the phenomenon of oscillating airflow in such upward roadways were simulated, and it was concluded that when the phenomenon of airflow oscillation occurs in parallel upward ventilated systems, the number of airflow oscillations is significantly reduced by increasing the initial airflow velocity. The amplitude of each oscillation is reduced. When the initial wind speed was 0.2 m/s, several wind flow reversals and airflow oscillations occurred. When the initial wind speed increased to 0.35 m/s, two wind flow reversals occurred, and the maximum wind speed difference after the reversal was 0.2 m/s. At an initial wind speed of 0.5 m/s, a single reversal of airflow was observed, but no oscillatory behavior was noted. After the reversal, the maximum wind speed difference was 0.16 m/s, and the maximum wind speed difference was 0.16 m/s in the range of 0.5 m/s-0.65 m/s. The difference in the reversal was 0.12 m/s. The study results are of great significance for preventing and controlling the phenomenon of underground airflow oscillation and ensuring the safe production of coal mines.