点火位置对污水管网可燃气体爆燃特性影响模拟研究

针对典型市政污水管网内可燃气体爆燃过程，采用流体动力学软件Fluidyn，建立了由顶端封闭、深度为4 m的竖直检查井和两端开口、长度各为20 m的水平井构成的管网模型，研究了不同点火位置（检查井上部、中部和下部）对甲烷爆燃特性的影响。研究结果表明:不同位置点火时，管网内测点压力时程呈现出亥姆霍兹振荡，各压力峰值曲线具有明显的分段性，且相同测点的数值接近；爆炸温度在点火位置附近出现最大值，其中上部点火时数值最大，中部点火时居中，下部点火时最小，但在水平井内温度峰值近似呈线性衰减并在端口出现最小值；与下部点火相比，上部和中部点火时，检查井和水平井连接处扩容效应造成火焰传播速度衰减显著，但在水平井内均近似呈线性增大并在端口出现最大值。

Simulation research on influence of ignition position on deflagration characteristics of combustible gas in sewage pipe network

Aiming at the deflagration process of combustible gas in typical municipal sewage pipe network,a pipe network model was established by using the fluid dynamics software Fluidyn,which consisted of a vertical inspection well with closed top and 4 m depth and a horizontal well with openings at both ends and 20 m in length.The influence of different ignition positions (at the top,middle and bottom of inspection well) on the deflagration characteristics of methane was studied.The results showed that when ignited at different positions,the curves of pressure vs.time of the test points in the pipe network presented the Helmholtz oscillation.The peak pressure curves had obvious piecewise characteristics,and the values of the same test point were close to each other.The maximum explosion temperature occurred near the ignition position,and the value was the largest with top ignition,followed by middle ignition,and the smallest with bottom ignition.However,the peak temperature in the horizontal well approximately presented the linear decrease,and the minimum value appeared at the port.Compared with the bottom ignition,the expansion effect at the junction of the inspection well and the horizontal well resulted in a significant attenuation of flame propagation velocity with the top and middle ignition,but it approximately presented the linear increase in the horizontal well and reached the maximum value at the port.