牙轮-PDC复合钻头井底流场CFD模拟研究

牙轮-PDC复合钻头是对硬地层采用碾压与刮切相结合破岩的一种新型钻头,随着其结构形式及破岩方法的改变,需要对其井底流场进行研究并提出新的水力结构设计。运用计算流体动力学理论,采用标准κ-ε模型以及封闭N-S湍流方程对某型复合钻头的井底流场进行了数值模拟计算,并分析了井底压力及流速、PDC刀翼齿面和牙轮体表面流速。研究结果表明,复合钻头设计原型的水力结构存在一定缺陷,可通过合理设计钻头体中心位置结构、调整中心喷嘴射流角度以及调整2个边喷嘴的设计来加以改进。

Research on Bottomhole Flow Field CFD Simulation of Composite Roller-PDC Bit

The composite roller-PDC bit is a new type of drill bit which conducts rock-breaking through rolling,scratching and cutting.With the change of its structural pattern and rock-breaking mode,it is necessary to make a study of its bottomhole flow field and put forward the new hydraulic design.Applying the theory of computational fluid dynamics(CFD),the closed N-S turbulence equation in the standard κ-ε model was adopted to conduct a numerical simulation calculation of the bottomhole flow field of some composite bit.The bottomhole pressure and flowrate,PDC blade tooth face and roller surface flowrate were analyzed.The research findings show that there exists some defect with the hydraulic structure of the design prototype of composite bit.The design of central nozzle can be improved by rational design of the structure of bit center position and adjustment of central nozzle jet angle.Change of jet angle can adjust the design of two side nozzles.