Study On Propagation Characteristics Of Shock Wave In Pipe Network And Simulation Of Catastrophic Process For Gas Explosion

The harm and destructiveness of mine gas explosion are very serious,which is the first of all kinds of disasters in coal mines.Once gas explosion accident happens,it will instantly produce blast shock wave,high temperature airflow,poisonous and harmful gas,which will cause the destruction of ventilation structure,the ventilation network airflow disorder,and suffocation.Considering the particularity and complexity of the process of gas explosion shock wave propagation,we need to grasp the temporal and spatial variation process of parameters in mine ventilation network timely and accurately,so as to provide technical support for underground disaster relief work.In the dissertation,the methods of theoretical analysis,experiment research,and numerical simulation were used to study propagation characteristics and attenuation rule of gas explosion shock wave in straight,turning,bifurcation,cross section abrupt pipe,A network,and parallel network.Based on these above,a three dimensional simulation system for the catastrophic process of gas explosion was developed.Taking a mine gas explosion accident case in China as research object,the application effect of simulation system was verified.The main results obtained are as follows:(1)The basic relations of explosion shock wave propagation were established,and the interaction relationships between shock waves of multiple explosions were analyzed.Based on the plane model of gas explosion,the relationships between overpressure,airflow velocity,propagation speed and propagation distance after the attenuation of gas explosion in straight lane were obtained.(2)A different gas explosion experimental system was built,and gas explosion experimental research of gas accumulation volume(8m,10m,11m filling length)was carried out.A modified formula for calculating the attenuation of gas explosion shock wave overpressure was obtained.It was found that,in turn or bifurcation pipe,gas explosion overpressure attenuation was mainly affected by turning or bifurcation angle,initial pressure,thereby establishing a coupling relationship between overpressure attenuation coefficient and turning,bifurcation angle,initial pressure.(3)Propagation characteristics of shock wave overpressure in A network was obtained by experiment research.It was found that when A network was symmetrical,explosion waveform and overpressure attenuation characteristics of symmetrical sides of A network and symmetrical position of corner pipe showed symmetrical characteristics.When asymmetric,the blocking rate of a pipe on one side was changed,and it was found that the increase of blocking rate could improve the overpressure of side shock wave.Propagation characteristics of shock wave overpressure in parallel network were obtained by experiment research.It was concluded that maximum overpressure showed a monotonic decreasing trend,and the trend of maximum overpressure variation along the two sides of parallel network was the same.(4)Propagation characteristics of shock wave overpressure in pipe break section was obtained by numerical simulation.It was found that the overpressure of shock wave decreased when the abrupt section became larger,and the overpressure of shock wave increased when the abrupt section became smaller,and the reflected wave overpressure value exceeded the overpressure values of initial incident wave.Based on these above,the relationships between overpressure attenuation coefficient,increase coefficient,reflection coefficient separately and the change rate of cross section,initial pressure were established(5)The unsteady state network solution model,airflow temperature propagation and mixing model,fire pressure model and propagation model of disaster gas in ventilation network were given.A method for determining the failure of ventilation structures by explosion shock wave overpressure was proposed.By analyzing the characteristics of each field of gas explosion,the field volume model in the period of gas explosion was proposed.Based on these above,the model of gas explosion field was set up,and the time series of field was analyzed.Taking the simulation of gas explosion catastrophe process as the core,a simulation platform integrating simulation computation,data management and spatio-temporal process visualization was constructed.(6)The simulation system was applied to simulate a mine gas explosion accident in China.The destruction of ventilation structure,the dynamic evolution of ventilation network structure,the propagation process of shock wave and the dynamic propagation process of disaster gas in the network were analyzed,and the effect of simulation system was verified.The research results not only have important theoretical and practical values,but also play an important guiding role in solving gas explosion accidents and the post disaster restoration of mine ventilation system.