Research On Secondary Explosion Process And Its Law In Confined Space

The gas explosion is one of the most serious disasters in the coal mine.Constantly,the gas explosion in coal mine brings about a secondary explosion.And it expands the scope,the casualties and the property losses of the gas explosion.There is an insufficient basis for secondary accident prevention and control because the research on the secondary explosion is limited.Because of this,this paper aimed at the secondary explosion problem caused by the gas explosion.A mathematical model for the secondary explosion was established after summarizing the research achievements of the gas explosion at home and abroad.The comparison between the gas explosion test data of the pipeline test platform and the simulation results of the fluid dynamics software was carried out.After studying the process of the secondary explosion in the double-reactor system as well as in the pipeline system with different concentrations,the relevant laws were obtained.On the base of the original model,a double-reactor explosion model was formed by adding a reactor on the right side of the model.The causes of the secondary explosion and its propagation laws were studied through setting methane gas on the right and left reactor.In the two-reactor model,the pressure wave generated by the gas explosion on the one side compressed and did work on the gas on the other side to increase its temperature and turbulent intensity.The increase of the magnitude of pressure and temperature led to the fall of the minimum ignition energy of the gas.Therefore,a local hot spot appeared on the pipe wall and a secondary gas explosion occurred.Owing to the existence of the local methane,the complexity of the gas explosion propagation with a double-sided gas contribution has greatly increased compared with the one with a single-side gas contribution in the two-reactor model.The phenomenon that two high-temperature regions,a 35.8% pressure peak off caused by the pressure wave offset formed by both side gas explosion and a low-pressure region in the slender pipeline appeared in the model.A gas driving effect toward the unburned methane caused by the beginning explosion pressure appeared in the pipeline.The migration direction of the local gas changed with the development of the explosion field within the pipeline.The gas detonated at the center of the pipeline.The change of local gas concentration affected the propagation law and its secondary explosion characteristics in the pipeline.With the increase of the local gas concentration in the pipeline,the pressure peak of the secondary explosion of gas increased first and thendecreased.The maximum of the pressure peak obtained when the local gas concentration was slightly larger than the equivalent concentration.Also,the high-temperature area,temperature peak,flame surface folds and the degree of the flame turbulence increased during that process.