Highlight The Research On The Gas Counterflow Criterion In Fresh Air Roadways

China ' s energy structure is dominated by coal,coal and gas outburst control work has been the first problem to face in production safety.When the coal and gas outburst accident occurs,the broken coal and rock mass is pressed,dumped or outbursted from the rock wall,accompanied by the migration of gas impact airflow,burying personnel and equipment.Therefore,in the case of intact anti-burst door and anti-countercurrent facilities,it is of theoretical and practical significance to analyze the attenuation law of outburst jet at the anti-burst door and master the gas countercurrent conditions under the coupling effect of mechanical wind pressure and outburst overpressure.Through theoretical analysis,physical similarity experiment and numerical simulation,this paper analyzes the spatio-temporal movement process and energy dissipation law of outburst jet under various types of roadways.The research results are as follows :The main energy sources and energy dissipation of outburst jet were studied by fluid mechanics and ventilation safety theory,and the motion characteristics and propagation attenuation laws of outburst shock wave under different roadways were analyzed.The results show that the main energy sources of outburst jet are coal elastic energy and gas expansion energy,and the energy dissipation is mainly coal crushing work,along-way resistance and local resistance.The outburst jet experiment under different outburst chamber pressure was carried out by similar physical experiment,and the pressure data were collected by the pressure sensor in the roadway.The experimental results show that when the outburst jet strikes the anti-outburst air door in the straight roadway,it will reflect and produce secondary impact with the forward outburst jet.In this process,the energy dissipation of the outburst jet is large,and the average attenuation rate is0.815.It is proved that the anti-outburst air door is effective to reduce the damage of the outburst airflow to the whole ventilation system and reduce the diffusion range of gas countercurrent.When the outburst jet enters the fresh air roadway from the return air branch roadway,it will be divided into two airflows,which migrates from the outlet and discharges the ventilation system rapidly under the action of negative pressure ventilator.The countercurrent migration in the direction of the two-way inlet blocks the effect of mechanical wind pressure in the fresh air roadway,but it will impact the fresh air due to inertial migration,resulting in the increase of local overpressure and the decrease of countercurrent velocity.Based on the fluid control equations such as continuity equation,momentum equation and energy equation,the outburst jet experiments under different outburst chamber pressures are numerically simulated by ANSYS Fluent software to verify the similar physical experiment results.In this paper,by analyzing the spatio-temporal movement process and energy dissipation law of outburst impinging jet under the action of anti-burst gate,the gas countercurrent law of fresh air roadway under the protection of anti-burst gate is obtained.The research results can provide certain theoretical reference for the prevention and control of gas countercurrent in the future.