基于CT三维重建煤骨架结构模型的渗流过程动态模拟研究

为了探究煤体微观结构中的渗流变化情况,以新疆大黄山气煤为研究对象,运用CT扫描和三维重建技术建立了含有孔裂隙的三维煤体骨架结构模型。在此基础上构建了一种能够反映动态渗流过程的流固耦合模型,并结合内置Navier-Stokes控制方程的ALE算法进行了渗流模拟。结果表明:渗流过程中,孔裂隙中每个点的流速都会存在一个速度峰值和稳定流速值;相较于裂隙结构,孔隙结构较差的连通性增大了其在模型前端的流体动能损耗,减缓了后续孔隙中流体的流动。初始流速影响了入水口处流速及流体密度的变化趋势,也改变了裂隙中速度峰值的变化规律,当初始流速值低于0.03 mm/s时,裂隙中速度峰值沿渗流方向呈现出"先增大后减小"的变化趋势,而当初始流速值大于0.03 mm/s时,速度峰值则沿着渗流方向逐渐减小。在低压力梯度条件下,孔裂隙的速度峰值与压力梯度之间存在非线性变化关系,而稳定流速值则随压力梯度的变化线性增大。研究成果为后续相关渗流影响因素的研究提供了一种新的思路。

Dynamic simulation of seepage process based on CT 3D reconstruction of coal skeleton structure model

In order to investigate the seepage change in the microstructure of coal,taking Xinjiang Dahuang Mountain’s gas coal as an example,using CT scanning and 3D reconstruction technology,a 3D coal skeleton structure model with pores and fissures is established.On this basis,a fluid solid coupling model which can reflect the dynamic seepage process is constructed.Then combined with the ALE algorithm with Navier-Stokes control equation,the numerical simulation is carried out.The results show that in the process of seepage flow,there is a velocity peak and a steady flow velocity at the each point of the pores and fissures.Compared to the fracture structure,the poor connectivity of pore structure increases the loss of fluid kinetic energy at the front of the model and slows the flow of fluid in the following pores.The initial flow velocity affects the variation trend of flow velocity and fluid density at the inlet,and also changes the peak velocity variation in the fracture.When the initial velocity is lower than 0.03 mm/s,the peak value of velocity in fractures shows a trend of “first increasing,then decreasing” along the seepage direction.When the initial velocity is greater than 0.03 mm/s,the velocity peak decreases along the direction of seepage.At low-pressure gradient condition,there is a nonlinear relationship between the velocity peak and the pressure gradient in the pore fracture structure,while the steady seepage value increases linearly with the increase of the pressure gradient.The results provide a new idea for the study of influencing factors of seepage in future research.