To study the development of imbibition such as the imbibition front and phase distribution in shale,the Lattice Boltzmann Method(LBM)is used to study the imbibition processes in the pore-throat network of shale.Throug...To study the development of imbibition such as the imbibition front and phase distribution in shale,the Lattice Boltzmann Method(LBM)is used to study the imbibition processes in the pore-throat network of shale.Through dimensional analysis,four dimensionless parameters affecting the imbibition process were determined.A color gradient model of LBM was used in computation based on a real core pore size distribution.The numerical results show that the four factors have great effects on imbibition.The impact of each factor is not monotonous.The imbibition process is the comprehensive effect of all aspects.The imbibition front becomes more and more non-uniform with time in a heterogeneous pore-throat network.Some non-wetting phases(oil here)cannot be displaced out.The displacement efficiency and velocity do not change monotonously with any factor.The development of the average imbibition length with time is not smooth and not linear in a heterogeneous pore-throat network.Two fitting relations between the four dimensionless parameters and the imbibition velocity and efficiency are obtained,respectively.展开更多
为了充分发挥光滑粒子流体动力学方法(smoothed particle hydrodynamics,SPH)在处理大变形和有限元(finite element method,FEM)问题时计算精度高的优势,提出了一种新型SPH-FEM耦合算法。该耦合算法在大变形区域使用SPH粒子离散,其余区...为了充分发挥光滑粒子流体动力学方法(smoothed particle hydrodynamics,SPH)在处理大变形和有限元(finite element method,FEM)问题时计算精度高的优势,提出了一种新型SPH-FEM耦合算法。该耦合算法在大变形区域使用SPH粒子离散,其余区域使用有限元离散。在耦合界面处将SPH粒子固结在有限单元,在有限元节点设置背景粒子,通过背景粒子的方式将有限元节点纳入到SPH临近搜索列表,消除了SPH边界效应,确保耦合界面物理量的连续性。使用该算法对圆柱形钢弹正冲击钢板发生冲塞破坏的过程进行了三维数值模拟,靶板参数的计算采用含损伤的Johnson-Cook模型和Grüneisen状态方程,模拟结果与实验吻合较好。展开更多
针对同一成型装药形成多模毁伤元问题,利用LS-DYNA程序,研究了单点起爆位置对爆炸成型侵彻体(explosively formed penetrator,EFP)成型的影响规律。当起爆点距离药型罩的轴向距离从0倍装药口径增加到0.72倍装药口径,EFP速度提高了37.8%...针对同一成型装药形成多模毁伤元问题,利用LS-DYNA程序,研究了单点起爆位置对爆炸成型侵彻体(explosively formed penetrator,EFP)成型的影响规律。当起爆点距离药型罩的轴向距离从0倍装药口径增加到0.72倍装药口径,EFP速度提高了37.8%,长径比增加了1倍多;优化设计成型装药结构,分析了主装药端面中心点起爆和药型罩顶点起爆爆轰波传播规律,实现了杆式EFP、EFP 2种模态的转换。通过X光成像实验进行了验证,实验结果与数值模拟结果吻合较好。展开更多
基金supported by the National Natural Science Foundation of China(12072347)the Excellent Training Plan of the Institute of Mechanics,Chinese Academy of SciencesCNPC New Energy Key Project(2021DJ4902).
文摘To study the development of imbibition such as the imbibition front and phase distribution in shale,the Lattice Boltzmann Method(LBM)is used to study the imbibition processes in the pore-throat network of shale.Through dimensional analysis,four dimensionless parameters affecting the imbibition process were determined.A color gradient model of LBM was used in computation based on a real core pore size distribution.The numerical results show that the four factors have great effects on imbibition.The impact of each factor is not monotonous.The imbibition process is the comprehensive effect of all aspects.The imbibition front becomes more and more non-uniform with time in a heterogeneous pore-throat network.Some non-wetting phases(oil here)cannot be displaced out.The displacement efficiency and velocity do not change monotonously with any factor.The development of the average imbibition length with time is not smooth and not linear in a heterogeneous pore-throat network.Two fitting relations between the four dimensionless parameters and the imbibition velocity and efficiency are obtained,respectively.
文摘为了充分发挥光滑粒子流体动力学方法(smoothed particle hydrodynamics,SPH)在处理大变形和有限元(finite element method,FEM)问题时计算精度高的优势,提出了一种新型SPH-FEM耦合算法。该耦合算法在大变形区域使用SPH粒子离散,其余区域使用有限元离散。在耦合界面处将SPH粒子固结在有限单元,在有限元节点设置背景粒子,通过背景粒子的方式将有限元节点纳入到SPH临近搜索列表,消除了SPH边界效应,确保耦合界面物理量的连续性。使用该算法对圆柱形钢弹正冲击钢板发生冲塞破坏的过程进行了三维数值模拟,靶板参数的计算采用含损伤的Johnson-Cook模型和Grüneisen状态方程,模拟结果与实验吻合较好。
文摘针对同一成型装药形成多模毁伤元问题,利用LS-DYNA程序,研究了单点起爆位置对爆炸成型侵彻体(explosively formed penetrator,EFP)成型的影响规律。当起爆点距离药型罩的轴向距离从0倍装药口径增加到0.72倍装药口径,EFP速度提高了37.8%,长径比增加了1倍多;优化设计成型装药结构,分析了主装药端面中心点起爆和药型罩顶点起爆爆轰波传播规律,实现了杆式EFP、EFP 2种模态的转换。通过X光成像实验进行了验证,实验结果与数值模拟结果吻合较好。
