采空区开区注氮防灭火的数值模拟研究

用迎风有限元法求解了采空区气体渗流方程和氧气的渗流-消耗-弥散方程,用图象显示了注氮时采空区的流态、氧浓度分布变化的流体力学过程和注氮防灭火机理.注氮气能改变采空区的漏风流态,并以氮气等量抑制工作面向采空区的漏风,减少了向采空区的供氧.在采空区的入风隅角处顺流注氮,有利于氮气沿漏风流势移动.注氮流量与氧的惰化浓度线位置近似呈反比例关系.给出用数值模拟确定注氮流量的方法.图7,参8.

Numerical simulation study of nitrogen injection process for fire prevention and extinguishment in goaf

The seepage equation of airflow movement in flow field of goaf and the seepage-dissipation-diffusion equation of oxygen concentration variation process during nitrogen injection have been solved by upwind finite element method,and the fluid mechanics process of nitrogen injection and the mechanics of fire prevention and extinguishment are described in graphic manner.While nitrogen injection in open region is performed at the air leakage side,the trend of nitrogen can be controlled according to the flow direction of air leakage in goaf,at the same time the air leakage quantity from working faces to goafs can be controlled.The relationship between nitrogen injection parameters and the state of airflow field and oxygen concentration distribution in goaf has been analyzed in detail,and according to the analysis,there is an approximate inverse proportional relationship between the quantity of nitrogen injection and the position where the oxygen concentration for fire prevention and extinguishment is 4mol/m3.A method of computer numerical simulation is presented to determine the parameters(flux) of nitrogen injection.7figs.,8refs.