Experimental study on the flow regime transition characteristics of gas radial seepage in fractured coal bodies around extraction boreholes
张天军刘荣涛潘红宇庞明坤武晋宇
ZHANG Tianjun;LIU Rongtao;PAN Hongyu;PANG Mingkun;WU Jinyu
西安科技大学 安全科学与工程学院西安科技大学 理学院
钻孔孔周煤体瓦斯径向渗流流态是反映抽采瓦斯渗流运动的重要因素之一。为探究钻孔孔周煤体的不同孔隙结构和瓦斯压力对瓦斯径向渗流运动特征的影响,分别制作了5种不同级配的含孔试样,利用自主设计的瓦斯径向渗流试验系统,采用稳态渗流法对含孔试样进行径向渗流试验研究,分析Forchheimer数和非Darcy误差随渗流速度与级配的变化规律,运用Hazen−Dupuit−Darcy方程和雷诺数理论得到了不同流态的流速区间和雷诺数范围。结果表明:① 通过对Forchheimer数和非Darcy误差随渗流速度变化曲线的分析可知,Forchheimer数随渗流速度呈二次多项式曲线增加,而非Darcy误差呈线性增加,Forchheimer数和非Darcy误差与孔隙结构密切相关,2者都随级配的增大而变大,说明渗流速度和孔周煤体的孔隙结构是瓦斯渗流偏离线性渗流的重要因素;② 利用Hazen−Dupuit−Darcy方程对瓦斯径向渗透流态进行表征和划分,随着渗流速度的增大,瓦斯径向渗流运动依次出现前达西、达西和Forchheimer流态,且
The radial gas seepage flow regime of the coal body around borehole is one of important factors reflecting the seepage movement of extracted gas. In order to investigate the effects of different pore structures and gas pressure on the radial seepage motion of gas in the perimeter of borehole, five kinds of pore-bearing coal samples with different gradations were made, and the radial seepage test was carried out on the pore-bearing coal samples by using the self-designed gas radial seepage test system and the steady-state seepage method to analyze the changes of the Forchheimer number and non-Darcy error with the seepage velocity and gradation, and the flow velocity intervals and the Reynolds number ranges of different flow regimes were obtained by using the Hazen-Dupuit-Darcy equation and the Reynolds number theory. The results show that: ① Through the analysis of the Forchheimer number and non-Darcy error with the change curve of seepage velocity, the Forchheimer number increases with seepage velocity in a quadratic polynomial curve, while non-Darcy error increases linearly, the Forchheimer number and non-Darcy error are closely related to pore structure, and both become larger with the increase of gradation, indicating that seepage velocity and pore structure of the coal body around the pore are important factors for gas seepage deviating from linear seepage; ② The Hazen-Dupuit-Darcy equation was used to characterize and delineate the gas radial permeability flow regime. With the increase of seepage velocity, the gas radial seepage motion appears in order of pre-Darcy, Darcy and Forchheimer flow regimes. The small-graded porous specimens with
孔周煤体径向渗流流态转捩孔隙结构
coal body around the drill hole;radial seepage;seepage flow regime;pore structure
主办单位:煤炭科学研究总院有限公司 中国煤炭学会学术期刊工作委员会