径向水平井自进式旋转射流钻头流场特性分析

为解决径向水平井钻进过程中破岩效率和自进能力的问题,设计了一种自进式旋转射流钻头。运用数值模拟方法,采用RNG k-ε湍流模型对所设计射流钻头的内外流场进行了三维流动特性分析,并分析了射流钻头结构参数对喷嘴流场特性的影响规律,进一步优化了自进式旋转射流钻头。结果表明,自进式旋转射流喷嘴外流场的轴心速度在喷嘴中心线上的速度最大,随着径向半径的增大,轴向速度迅速减小;切向速度沿喷嘴径向呈现出经典的"N"形分布,有利于增大射流破碎岩石的深度和破碎面积;径向速度呈轴对称分布,存在明显的漫流层,有助于岩屑的脱离;自进式旋转射流钻头导向叶轮的螺距和导叶数量,对射流速度有着重要的影响;喷嘴直径对射流流场特性的影响较大。经过优化,得到射流钻头的叶轮螺距16mm,导叶数为2,喷嘴直径为1mm。

Flow Field Study on Self-propelled Conical Jet Bit for Radial Horizontal Drilling

A novel self-propelled conical jet bit was designed to settle the problem of rock breaking efficiency and self-propelled ability. The 3D flow characteristics of flow fields inside and outside the designed jet bit were analyzed based on numerical method and RNG k- ε turbulent model. Furthermore,the influence of the jet bit structural parameters on flow field characteristics of the jet nozzle was investigated for optimizing the novel jet bit. The experimental results show that the maximum axial velocity of flow field outside the nozzle is on the centerline of the nozzle and the axial velocity rapidly drops with the increase of radial radius. The tangential velocity along the nozzle radial shows classical"N"pattern distribution,which is beneficial for producing larger rock breaking area and depth. The radial velocity exhibits axial-symmetric distribution and has an obvious cross flow layer in favor of cleaning the cuttings. The number of guide vane and the screw pitch of the oriented impeller for the jet bit have a significant influence on jet velocity. In addition,the nozzle diameter has great effect on flow field characteristics of the jet flow. After optimization,the value of the screw pitch is 16mm,the number of guide vane is 2 and the nozzle diameter is 1mm.