非均质孔隙率采空区氧化升温规律四维动态模拟

4D dynamic simulation of coal oxidation heating law in gobs with heterogeneous porosity

运用Fluent动网格模型实现采空区的四维动态变化,并用用户自定义函数将煤低温氧化动力学机理及非均质孔隙率函数编入Fluent中,结合时间和空间,对U+L型通风系统采空区升温规律进行四维动态模拟研究.研究表明:非均质孔隙率四维动态模型能更真实地反应孔隙率的空间与时间变化,空间某一位置的孔隙率随时间呈负指数递减;工作面推进速度越大,采空区升温速率越小,推进速度为3.6 m·d-1时平均升温速率仅为推进速度为1.2 m·d-1时的1/5;然而,推进速度越大,高温点的深度越大,不利于自燃的预防;尾巷的存在使得温度场范围扩大,温度升高,CO主要从尾巷流出,尾巷释放的CO量是回风巷CO释放量的10倍.最后利用现场实测的数据对结果进行验证,表明模拟结果是正确可信的.

Using the Fluent dynamic mesh model to realize the 4D dynamic movement of a gob and inputting the kinetic mechanism of coal low-temperature oxidation and the dynamic change of heterogeneous porosity into Fluent through the user defined function,4D dynamic simulation is performed on the spontaneous heating law in a gob for U ＋ L ventilation of a certain mine. The results show that unsteady heterogeneous porous media can be more realistic in response to the change of porosity,which exponentially decreases with time. The greater the advancing speed of the working face,the smaller the heating rate,and the average heating rate at an advancing speed of 3. 6 m·d^-1 is 1 /5 of that at an advancing speed of 1. 2 m·d^-1 . However,the higher the advancing speed,the deeper the depth of the high temperature region,which is unfavorable for the prevention from spontaneous combustion of coal. Because of the existence of a tail roadway in the gob,the temperature field expands,the temperature rises,the main way to release CO is the tail roadway,and the amount of CO from the tail roadway is 10 times that from the outlet. Finally,the results are verified by the field test data,indicating that the simulation results are correct and reliable.