叶轮式井底盘阀脉冲射流钻井工具性能分析与优化

为进一步提高钻井效率，基于井底不对称流场在清岩与辅助破岩等方面所具有的良好效果，设计了一种以小型水动力叶轮为驱动力来源的叶轮式井底盘阀脉冲射流钻井工具，并通过数值模拟及试验对水动力叶轮与该射流工具进行了优化设计。利用计算流体力学软件Pumplinx对叶轮区域进行了全工况数值模拟，通过分析内部流场的压力、速度以及湍动能的分布特性，总结了叶轮转速与阻力扭矩及轴向力之间的响应关系；通过在该射流工具进口段布置导流块、对叶片轮毂端进行光顺处理以及选取合适的叶片包角等优化措施，让叶轮进口流场得到改善的同时，提高了叶轮的水动力特性并消除了部分轴向力。模拟结果显示，初始叶轮在75 r/min转速下可克服的自然负载阻力扭矩从1.07 N·m提高到3.93 N·m。研究结果表明，所述优化方案能大幅提高叶轮式井底盘阀脉冲射流工具的脉冲性能，优化效果十分显著。 

Performance Analysis and Optimization of a Pulse Jet Drilling Tool with an Impeller-Type Bottom Hole Disc Valve

To further improve drilling efficiency,a bottom-hole pulse jet drilling tool with a disc valve driven by a small hydrodynamic impeller was designed based on the good performance of a bottom-hole asymmetric flow field for cuttings cleaning and auxiliary rock breaking. Performance was optimized in the hydrodynamic impeller and jetting tool through numerical simulation and experiments. The numerical simulation for fluid around impeller was carried out by using the computational fluid dynamics software, Pumplinx, in full operational conditions. The response relationships among impeller rotary speed, resistance torque and axial force were summarized by analyzing the pressure, velocity and turbulent kinetic energy distribution of internal flow fields. The inlet flow field and hydrodynamic performance of impellers were improved while the axial force was partially eliminated by setting a guide block at the inlet of jet tools, performing smoothing treatment on blade hubs and selecting appropriate blade angle. Simulation results showed that the resistance torque of natural load on impeller can be increased from 1.07 N·m to 3.93 N·m initially at the rotary speed of 75 r/min. Research results indicated that the optimal measures could improve the pulse performance of impeller-type bottom hole disc valve in pulse jet tools, with significant optimization results.