基于排屑性能的扩孔气动冲击器设计方法

Design Method of Reaming Pneumatic Impactors Based on Its Cuttings Removal Performance

为了提高硬质地层中扩孔气动冲击器的排屑性能,基于岩屑颗粒在排屑流场中的临界流速原则,运用计算流体力学理论和Fluent仿真软件,研究了一种与排屑性能相关的扩孔气动冲击器设计方法,并将该设计方法在反向扩孔气动冲击器上进行应用.得到设计前后冲击器排屑流场内气相速度分布规律,岩屑颗粒速度及轨迹变化情况和环路内岩屑颗粒浓度分布情况.研究结果表明:反向扩孔气动冲击器排屑流场环路内岩屑颗粒临界流速为6.02 m/s,采用该设计方法能够有效地增加反向扩孔气动冲击器的排屑性能,使得排屑流场环路内气流速度增加到10 m/s左右,岩屑颗粒在排屑流场的停留时间减短,流场内颗粒浓度分布范围由0~100 kg/m3下降到0~4 kg/m3.

In order to improve the cuttings removal performance of reaming pneumatic impactors in hard layers, the computational fluid mechanics theory and Fluent simulation software were employed to find out a design method based on the critical velocity principle of cutting particles, which is related to the cuttings removal performance of reaming pneumatic impactors and then it was applied to the back-reaming pneumatic impactor. The speed distribution regularities of gas phase,the change of cutting particles’ velocity and trajectory,and the concentration distribution of cutting particles in the flow field of the back-reaming pneumatic impactor were obtained. The results showed that the cutting particles ’ critical velocity of the back-reaming pneumatic impactor in the cuttings flow field is 6. 02 m/ s. The design method related to cuttings removal performance can effectively strengthen the cuttings removal performance of the back-reaming pneumatic impactor,and the velocity of gas phase increases to 10 m/s in the flow field. The time when cutting particles remain in the flow field is shortened, and the value of particle concentration distribution range in the flow field decreases from 0-100kg/m^3 to 0-4kg/m^3.