矿山钻孔救援反循环钻头设计与流场模拟

Structure design of reverse circulation bit for drilling rescue and its internal flow simulating

针对钻遇破碎、漏失等复杂地层时反循环形成效果差,孔口返风严重这一实际问题,根据柯恩达附壁效应的基本原理,设计出一种煤矿应急钻孔救援用新型强力抽吸反循环钻头。借助流体分析软件FLUENT对钻头内部流场进行数值模拟。结果表明,相同条件下强力抽吸式钻头内部最大负压值达到20 k Pa,而普通内喷孔式反循环钻头的负压值为15 k Pa;强力抽吸式钻头环空边界抽吸气体的质量流量为0.039 kg/s,而普通内喷孔式反循环钻头环空边界抽吸气体的质量流量为0.026 kg/s,抽吸量提高到原来的约1.5倍,内部流场模拟显示其性能优于普通反循环钻头。

Aiming at solving the problem of poor effect of reverse circulation when complex strata were met, based on Coanda effect, a new type of reverse circulation drilling bit which has powerful suction force was designed. Engineering fluid dynamics software-FLUENT was used to simulate the distribution of pressure and velocity field. The conclusions obtained are that the maximum negative pressure in the powerful suction type bit is up to 20 kPa, while the maximum negative pressure in the ordinary nozzle type reverse circulation bit is approximately 15 kPa, and that the suction mass flow for the annular boundary in the powerful suction type bit is 1.5 times higher than that in the ordinary nozzle type bit, which shows a better performance of the powerful suction type reverse circulation bit.