基于Fluent的空气射流切削式反循环钻头参数优化

针对黄土地层,提出利用空气代替钻井液的反循环气体喷射技术。但现有技术对反循环气体喷射钻头切削土体的能力没有具体优化讨论。利用fluent软件,优化反循环喷射钻头结构参数,对不同底喷孔直径、底喷孔数量、底喷孔扩大段直径、底喷孔扩大段数量、喷射孔数量5个结构参数进行模拟分析。分析结果表明,在进风流量一定的情况下,增加底喷孔的数量或增大底喷孔的直径会削弱钻头的空气射流切削能力和反循环能力。底喷孔直径为3 mm,底喷孔个数为2个,底喷孔扩大段直径为8 mm,底喷孔扩大段长度为5 mm,内喷孔数量为5个时,反循环喷射钻头喷射能力和反循环能力最优。

Parameter Optimization of Air-jet-cutting Drill Bit with Reverse Circulation Technique Based on Fluent Software

In view of the loess formation, reverse circulation air-jet-cutting technique was proposed with air instead of drilling fluid. The bit structure parameters were optimized by Fluent software, the parameters of different diameters of bottom jet orifices, the number of bottom jet orifices, the diameters of bottom jet orifice enlarged sections, the number of bottom jet orifice enlarged sections and the number of bottom jet orifices were stimulation analyzed. The results show that in the case of a certain inlet air flow, air-jet-cutting and reverse circulation capacity of the drill bit would be weakened while increasing the diameter and number of bottom jet orifices. The best performance of air-jet-cutting and reverse circulation capacity can be achieved by the design structure with 2 bottom jet orifices of 3mm in diameter, the bottom jet orifice enlarged section of 8mm and 5mm in the diameter and the length respectively and 5 internal jet orifices.