基于SPH方法粒子射流破岩数值模拟与实验研究

钻井液中加入体积分数为1%~3%的钢质粒子在钻头喷嘴处高速喷出冲击岩石，实现了粒子射流冲击和钻头机械联合破岩，有效提高了破岩效率。利用瞬态非线性动力学有限元模拟软件，基于光滑粒子流体动力学(smoothed particle hydrodynamics，SPH)方法，考虑流体对粒子射流冲击的影响，建立了粒子射流冲击破岩的物理模型，获得了粒子射流参数对破岩体积的影响规律，进行了室内实验验证，验证了SPH方法的有效性。结果表明:粒子射流冲击岩石表面形成规则的V型冲击坑；同条件下粒子射流破岩体积是水射流破岩体积的2~4倍；随着粒子射流冲蚀时间的增加，粒子射流破岩体积不断增加，但破岩效率降低；粒子射流压力大于10 MPa后，粒子射流破岩效率迅速增大；喷射角度大于6°后，破岩效率迅速减小。

SPH-based numerical simulation and experimental study on rock breaking by particle impact

Added into the drilling fluid in a volume portion of 1％ to 3 ％,particles are capable of striking the rock with a high velocity after erupting from the bit nozzle and breaking the rock by particle impact combined with the mechanical action of the bit nozzle,thus greatly increasing the rock breaking efficiency.Using the transient nonlinear dynamics finite element simulation software and considering the influence of water jet,we established the physical model of rock breaking by particle impact based on the smoothed particle hydrodynamics (SPH) method,investigated the influence of the particle jet's parameters on the rock breaking volume,and verified the simulation results by comparing them with those of the indoors experiment which could verify the effectiveness of the SPH simulation method.Our results show that a regulation V-shaped crater is formed by the particle jet impact;the rock breaking volume resulting from this particle jet impact is 2 to 4 times that of the volume from the water jet under identical conditions.The rock breaking volume increases over time,but in the meantime the rock breaking efficiency decreases.When the pressure of the particle jet is above 10 MPa,there is a great increase of the rock breaking efficiency.When the jet angle is above 6°,there is a quick decrease of the rock breaking efficiency.