Abstract: Numerical simulation of downhole flow field of jet generated by PDC bit with asymmetrical distributed nozzles and different jetting ways was made by using preconditioning method and coupling with K-Ε two-equation model to close turbulent N-S equation.The available data were analyzed in detail.It is shown that the topology is similar to that of single-nozzle jetting.The asymmetrical distribution of nozzles on drill bit and inclined jetting can improve the downhole flow obviously,greatly reduce the backflow at bottom of hole resulted from symmetrical nozzles' locations and perpendicular jetting.The jetting style has not much effect on the height of sweeping layer.In addition,the bit damage caused by rotary fluid impact is of less chance.

Key words: multi-nozzle drilling bit, jet, downhole flow field, numerical simulation

摘要： 全面考虑三维、旋转、非对称多个喷嘴射流等多种因素,对垂直和倾斜射流分别进行了数值模拟,并详细分析了井底和钻头间各面上的数据。布置了非对称分布的4个喷嘴射流,明显地改善了井底流动状况。喷嘴倾斜射流能更好地加强井底流体的携带能力,彻底清除滞流或回流。但须注意在钻头表面上布齿时要避开涡,以减少流体对齿的冲蚀.

关键词: 多喷嘴钻头, 非对称, 射流, 三维流场, 数值模拟