建立了由反向扩孔气动冲击器排气孔到后封头的排屑流场,运用计算流体力学理论和FLUENT仿真软件研究了冲击器工作过程中尾气的携岩特性。基于冲击器的结构和工作原理,对气固两相排屑流场进行了数值仿真模拟,进而得到流场的气相特性以及岩屑颗粒运动轨迹和浓度分布规律。结果表明：冲击器排气孔尾气进入排屑流场后流速降低,流场压力由入口到出口逐渐降低;岩屑颗粒向流场底部聚集,颗粒平均浓度沿着远离入口方向变化不大,最大浓度沿着远离入口方向逐渐下降,最终趋于平稳。分析了钻进速度和尾气流量对携岩特性的影响,结果表明：随着钻进速度的增加尾气携岩能力下降,额定工作压力0.8 MPa时钻进速度应小于12.6 m/h;随着尾气质量流量的增加携岩能力提高,施工时应该在保证冲击器工作性能的情况下适当增加尾气质量流量。图12表1参13
The flow fields of chip removal from the impactor’s exhaust hole to its rear head were established to study the cuttings carrying characteristics of back-reaming pneumatic impactor exhaust by utilizing the computational fluid dynamics theory and simulation software Fluent. Based on the structure and working principle of the impactor, the gas solid two phase flow was simulated, and the gas phase characteristics of the flow field and the moving trajectory and concentration distribution of particles were obtained. The research shows that: once the exhaust enters the field its speed will slow down and the field pressure will gradually decrease from the entrance to the exit; cuttings particles will gather around the bottom and there is minor variation in their average concentration as they are distributed along a contrary direction against the entrance while the maximum concentration descends along the same direction and finally becomes stable. Moreover, the effect of drilling speed and exhaust mass flow of the impactor on the solid carrying characteristics was analyzed. The result demonstrates that: as the drilling speed increases, the carrying ability of exhaust decreases and when the rated operation pressure is 0.8 MPa, the drilling speed should be less than 12.6 m/h; as the mass flow rate of exhaust increases, the carrying ability increases as well, and the mass flow rate should be moderately increased under the condition of ensuring the working performance of the impactor.
[1] 侯树刚, 陈静. 非开挖技术的发展研究[J]. 科技进步与对策, 2003(S1): 232-233.
HOU Shugang, CHEN Jing. Development of trenchless technology[J]. Science & Technology Progress and Policy, 2003(S1): 232-233.
[2] 徐绍军, 徐大鹏, 徐海良, 等. 气动回扩锤的计算机仿真与优化研究[J]. 工程机械, 2008(1): 16-19.
XU Shaojun, XU Dapeng, XU Hailiang, et al. Computer simulation and optimazation of pneumatic back reamer[J]. Construction Machinery and Equipment, 2008(1): 16-19.
[3] MALARD F, DATRY T, GIBERT J. Subsurface sediment contamination during borehole drilling with an air-actuated down-hole hammer[J]. Journal of Contaminant Hydrology, 2005, 79(3): 156-164.
[4] 韩占忠, 王敬, 兰小平. FLUENT流体工程仿真计算[M]. 北京: 北京理工大学出版社, 2004.
HAN Zhanzhong, WANG Jing, LAN Xiaoping. Engineering simulation and calculation of fuild by FLUENT[M]. Beijing: Beijing Institute of Technology Press, 2004.
[5] 张涛, 李红文. 管道复杂流场气固两相流DPM仿真模型优化[J]. 天津大学学报(自然科学与工程技术版), 2015, 48(1): 39-48.
ZHANG Tao, LI Hongwen. Simulation optimazation of DPM on gas-solid two-phase flow in complex pipeline flow filed[J]. Journal of Tianjin University(Science and Technology), 2015, 48(1): 39-48.
[6] WANG K, PAN H, LIU Z. Numerical simulation on dense phase pneumatic conveying diversion characteristics in branch pipeline[J]. Journal of University of Jinan, 2013, 27(3): 303-308.
[7] 柳贡慧, 宋廷远, 李军. 气体钻水平井气体携岩能力分析[J]. 石油钻探技术, 2009, 37(5): 26-29.
LIU Gonghui, SONG Tingyuan, LI Jun. Analysis on cutting carrying capacity of gas in gas drilling for horizontal well[J]. Petroleum Drilling Techniques, 2009, 37(5): 26-29.
[8] HUBER N, SOMMERFELD M. Modelling and numerical calculation of dilute-phase pneumatic conveying in pipe systems[J]. Powder Technology, 1998, 99(98): 90-101.
[9] 周方奇, 施安峰, 王晓宏. 压裂油藏导流裂缝多相流动的高效有限差分模型[J]. 石油勘探与开发, 2014, 41(2): 239-243.
ZHOU Fangqi, SHI Anfeng, WANG Xiaohong. An efficient finite difference model for multiphase flow in fractured reservoirs[J]. Petroleum Exploration and Development, 2014, 41(2): 239-243.
[10] 郭建华. 气体钻井环空气固两相流动数值模拟研究[D]. 成都: 西南石油大学, 2006.
GUO Jianhua. Numerical simulation of annular gas-solid two-phase flow in gas drilling[D]. Chengdu: Southwest Petroleum University, 2006.
[11] YAKHOT V, ORSZAG S A. Renormalization group analysis of turbulence: I, Basic theory[J]. Journal of Scientific Computing, 1986, 1(1): 3-51.
[12] FAN Chun. Plug flow dense phase pneumatic conveying[J]. Advances in Mechanics, 2002, 32(4): 599-612.
[13] SAVAGE S B. Analyses of slow high-concentration flows of granular materials[J]. Journal of Fluid Mechanics, 1998, 377: 1-26.
