PDC钻头水力结构优化设计研究

在PDC钻头工作过程中，钻井液对钻头体表面的冲洗、冷却和润滑是保证钻头正常工作的一个非常重要的条件。对PDC钻头而言，水力结构（主要是中心水眼和冠部水道）设计的重要性尤其突出。以前,对钻头水力系统研究只能通过实验的方法进行,研究周期长、成本高、结构调整不方便，而数值模拟的方法在几年前还不成熟，甚至静态的复杂结构流场问题基本无法解决。为此，在提出PDC钻头水力结构优化设计原则的基础上，对PDC钻头的三维流场进行了数值模拟。模拟中考虑了钻头的喷嘴布置位置、直径、数量以及切削齿对流场的影响。计算结果表明，原设计在喷嘴布置位置和喷射角度上存在不足，以此为基础进行了水力结构的优化设计。文中的研究成果成功地应用在新型钻头水力结构的设计中，研究方法为PDC钻头水力结构优化分析奠定了理论基础。

STUDY ON OPTIMIZED DESIGN OF HYDRAULIC STRUCTURE FOR PDC BITS

During PDC bit running, it is very important to guarantee the bit normally working for the drilling fluid to wash, cool and lubricate the bit body. As for PDC bits, the hydraulic structural design is much more important. In the past, the study on the hydraulic system of bits can be conducted only by experimental methods, which make the study cycle long, the cost high and the structural adjustment not easy. And the numerical simulation method was not perfect several years ago, which can't even solve the problem of static flow field with complicated structure. So, based on the principle of optimized design of hydraulic structure for PDC Bits, the numerical simulation is conducted for the 3-D flow field of PDC bits. The influence of bit cutting teeth and its assign position, diameter and quantity of jet nozzles on the flow field is taken into account in the simulation. The calculating results show the original design has defects on the assign position of jet nozzles and the jet angle. According to the study results, it is conducted the optimized design of the hydraulic structure. The study results are successfully applied on the hydraulic structure design of new bits. The study method provides the theoretical basis for the analysis of hydraulic structure optimization of PDC bits.