多孔喷嘴破岩钻孔特性的实验研究

Experiment study on water jet breaking rock by multi-orifice nozzle

采用自行研制的实验装置研究了孔数和水力参数(冲蚀时间、喷嘴压降、喷距、围压)对多孔喷嘴破岩效果的影响规律。结果表明:喷嘴孔数越多,成孔形状越圆整;破岩效果随着射流压力的增大而呈线性增加;0围压条件下多孔喷嘴存在获得最大破岩体积和孔深的最优喷距约为5～6倍喷嘴当量直径。在围压条件下,多孔喷嘴破岩效果随着围压的增大而大幅下降;当量喷嘴直径相同时,破岩效果随孔数的增加而减小;在保证钻孔孔径的情况下,减少孔眼数量有利于提高多孔喷嘴破岩效率。实验结果可为超短半径水平钻孔射流钻头设计提供依据。

The experiments were conducted for 6 types of multi-orifice nozzles on water jet breaking rock,and the factors were analyzed with the rock breaking effect including numbers of nozzle orifices,hydraulic parameters such as erosion time,nozzle pressure drop,spray distance and confining pressure value.The results show that the more numbers of nozzle orifices,the more rounded shape of the jet drilling hole;rock breaking effect increases with the jet pressure drop increases linearly;under atmosphere submerged conditions,the optimal standoff distance for gaining the maximum hole depth and rock breaking volume is about 5 to 6 times of the equivalent nozzle diameter.In the confining pressure,with the confining pressure increases,a substantial decline in rock breaking effects,the breaking effect of the multi-orifice nozzle with equivalent diameter decreases with the growth of confine pressure.In the case of guaranteeing drilling diameter,to reduce the number of orifices helps to improve the efficiency of the nozzle breaking rock.The results can offer some helps for the jet bits design in the ultra-short radius radial horizontal drilling.