Pang Mingkun, Zhang Tianjun, Meng Yukai, Ling Zhiqiang
Key Laboratory of Western Mine Exploitation and Hazard Prevention of the Ministry of Education, Xi'an, People's Republic of China.
College of Safety Science and Engineering, Xi'an University of Science and Technology, 58, Yanta Mid. Rd., Xi'an, 710054, Shaanxi, People's Republic of China.
Sci Rep. 2021 Nov 29;11(1):23030. doi: 10.1038/s41598-021-02524-4.
Accurate determination of the permeability of crushed coal medium is the basis for the study of their permeability characteristics. To investigate the permeability characteristics of this special porous medium composed of crushed coal particles, the permeability parameters of crushed coal specimens of different initial porosities were measured by designing a lateral-limit compression seepage test system. Parameters were determined separately for specimens of different initial porosities. (1) the Reynolds number distribution region characterising the seepage state was determined and obtained. Specimens with initial porosity distribution between 0.02 and 0.08, and seepage Reynolds number distribution in the low-permeability zone, under Darcy flow; (2) the intrinsic permeability of the crushed coal medium was obtained by using the Ergun equation. The complex inverse proportional relationship between the drag coefficient and Reynolds number was derived; (3) Through the determination of the permeability of the crushed coal medium, the mean value of βK value was obtained to be about 45.7, and the analysis of the permeability of porous medium can determine its critical permeability. The relationship between the Forchheimer number Fo and critical Reynolds number was measured. The results indicate that it conforms to a linear distribution. In-depth analysis of these two parameters can be used to explore the flow transition process between laminar, transition, and turbulent flow. This study provides insight into the permeability characteristics of the media in fractured coal bodies.
准确测定碎煤介质的渗透率是研究其渗透特性的基础。为了研究这种由碎煤颗粒组成的特殊多孔介质的渗透特性，通过设计侧限压缩渗流试验系统，对不同初始孔隙率的碎煤试样的渗透参数进行了测定。分别测定了不同初始孔隙率试样的参数。(1)确定并得到了表征渗流状态的雷诺数分布区域。初始孔隙率分布在0.02至0.08之间的试样，渗流雷诺数分布在低渗透区，处于达西流状态；(2)利用厄贡方程得到了碎煤介质的固有渗透率。推导了阻力系数与雷诺数之间复杂的反比例关系；(3)通过测定碎煤介质的渗透率，得到βK值的平均值约为45.7，对多孔介质渗透率的分析可以确定其临界渗透率。测定了福希海默数Fo与临界雷诺数之间的关系。结果表明，它符合线性分布。对这两个参数进行深入分析，可用于探索层流、过渡流和湍流之间的流动转变过程。本研究为裂隙煤体中介质的渗透特性提供了见解。
