煤与瓦斯突出过程中煤-瓦斯两相流的运动状态

摘要

运用经典气体动力学理论,对突出孔洞内煤-瓦斯两相流的运动参数进行了一维讨论,推导了压力、密度、速度及流量等参数之间的数学函数关系,分析了突出过程中煤-瓦斯两相流流动的临界状态以及与其相关的两相流声速理论,并通过数值模拟和现场实例对临界流动理论进行了直观描述。在煤与瓦斯突出过程中,煤-瓦斯两相流的出口流动状态与孔洞形态、瓦斯压力、煤体破坏速度、瓦斯含量等因素密切相关。当两相流在孔口达到并超过临界状态时,由于突出孔洞口小腔大的形状限制了瓦斯流的完全膨胀,此时喷出的瓦斯流处于未完全膨胀状态。大量未完全膨胀状态的瓦斯流在巷道空间的瞬间膨胀可产生巨大的动力效应,从而严重破坏矿井生产设备和通风设施。临界运动状态是影响煤与瓦斯突出动力效应的关键因素之一,它对煤与瓦斯突出灾害的预警和防护都有重要意义。%Applying classic gas dynamics theory,carried on the one-dimensional analysis to the motion parameters of coal-gas flow in the outburst hole,and deduced the relational expression between the motion parameters（containing of velocity,current capacity and density etc.） of bursting coal-gas flow and gas pressure in the hole,then discussed the critical state and the sound velocity theory in coal-gas flow.In the process of coal and gas outburst,the flow state of coal-gas flow has intimate relationship with several factors,such as hole shape,gas pressure,coal break velocity,gas content and so on.The normal nozzle shape of outburst hole restricts the complete expansion of gas flow,and the critical velocity of coal-gas flow at the mouth of outburst hole is the sound velocity in two phase flow.The very state is called critical state,and the coal-gas flow bursting out is underexpanded.Once the coal-gas flow exceeds the critical state and the critical pressure is much greater than the roadway pressure,the fast expansion of high-volume under-expanded coal-gas flow will make a high-intensity dynamic effect and severely destruct mining production and ventilation facility.The critical state has the very tremendous significance on both controllability and destructiveness of the entire coal and gas outburst system.