Study On The Influence Of Combustible Gas Deflagration Characteristics In Gas-liquid Coexistence Confined Space

Combustible gas is often accumulated in typical confined Spaces such as municipal sewage pipe network and coal mine roadway,which is very easy to cause gas explosion accidents and heavy casualties.Although researchers within the limited space on related research on flammable gas explosion characteristics,but not fully combined with the actual pipe network,the structure and characteristics of the roadway and limited space,especially for water storage,the ignition position,check well depth,the influence of different gas composition and concentration of less involved,for its gas explosion characteristic,the research is still relatively insufficient,such as disaster evolution restrict its explosion disaster mechanism are revealed,and the development of prevention and control technology.Therefore,a self-designed small-size explosion experimental platform was built to carry out comparative experiments under different water level heights and methane concentrations to study the development and variation rules of deflagration pressure,temperature and flame.In addition,based on the fluid dynamics software Fluidyn,a large-scale pipe network model consisting of vertical inspection Wells and horizontal Wells was established to study the effects of different ignition locations,inspection well depths,and different gas compositions and concentrations on methane deflagration characteristics.（1）A self-designed and built small-size explosion experiment platform,which includes pipeline system,gas filling system,liquid injection system,ignition and data acquisition system,which can realize flammable gas deflagration experiment under different water level and height conditions.（2）Comparison experiments under different water level heights and methane concentrations were carried out using the self-designed explosion experimental platform.The results show that,compared with no water storage,when the water level is 2 cm,there is liquid water endothermic cooling during the deflagation process,resulting in the occurrence of double-peak or multi-peak structure in the pressure time history curve.Water storage and heat absorption vaporization and water vapor slow down the rise of deflagration temperature of methane with different concentrations,change the shape of deflagration flame front,and reduce the flame propagation speed.Compared with the condition without water storage,when the water level is 2 cm,the mean value of the peak deflagration pressure and the mean value of the peak temperature decrease in the range of 6.5%～12.5%methane concentration is 23.76%and 13.82%respectively.（3）Fluidyn with fluid dynamics software,set up by the top closed,depth of（2 m,4 m and 6 m）and openings on both ends of the vertical inspection Wells and the length of up to 20 m of the horizontal well network model,and studied the different ignition location（check well,middle and bottom）and check the well depth influence on methane explosion properties,it is concluded that the ignition position of different impact on the explosion flame propagation speed is bigger;The depth of the inspection well has little effect on the peak explosion pressure and the peak explosion temperature,but has a stronger effect on the flame propagation velocity,especially at the bottom of the inspection well.With the increase of the depth of the inspection well,the increase of the flame propagation velocity has the maximum value.（4）A pipe network model consisting of a vertical inspection w ell with a depth of 4 m at the top and a horizontal well with an o pening length of 20 m at both ends was established to study the ef fects of different gas compositions(6%CH₄,6%CH₄+1%C₈H₁₈)and concentrations(2%,4%and 6%C₈H₁₈)on methane deflagration char acteristics.It is concluded that the explosion pressure peak,explosio n temperature peak and flame propagation velocity of the mixture o f 6%CH₄ and 1%C₈H₁₈ are significantly higher than those of 6%CH₄.When the oil and gas concentration is 2%,4%and 6%resp ectively,the overall performance is that with the increase of oil an d gas concentration,the peak value of explosion pressure,explosion temperature and flame propagation velocity continue to decrease.