Ni Hongjian

Analysis on Modulation Principle of Mechanical Spring Valve Block-Type Pulse Jet

To take full advantage of the bottom-hole hydraulic energy to improve the drilling rate, it is proposed the technique assumption that using mechanical spring valve periodically is to block the fluid pathway, and modulating pulse jet is to increase the drilling rat. The internal flow field of mechanical spring valve block-type(MSVBT) device is anslyzed with the numerical simulation method, and confirmed the feasibility of modulating the hydraulic pulse. Based on simulation results, the principle prototype of MSVBT pulse jet was developed. The results of jet rock breaking were shown that as the pump pressure increased, the pressure fluctuation was increasing, and effects of the jet rock breaking was gradually improved, significantly better than continuous jet, which was proved the modulation principle feasibility of MSVBT pulse jet. The reaults are provided the basis for the drilling tool and related technologies development.

Study of Different Angle Inner Nozzle Flow Field Based on Suction-Type RC Bit

In order to improve the reverse circulation(RC) pumping performance and enhance the effect of RC, the suction-type RC bit on the basis of ejection theory was designed. And with theoretical calculations, computational fluid dynamics(CFD) and experiment, pressure field and velocity field produced by different angle inner nozzles were studied. It was discussed the feasibility of suction principle in enhancing RC effect, and at the same time it was provided a theoretical basis to optimize the design of RC bit. The results show that applying ejectors to improve RC performance is absolutely feasible. Also, the pressure field and velocity field produced by the suction-type RC bit, as the injection angle increases, the pumping capacity both intersection inner nozzle and spiral inner nozzle is decreased, and the spiral inner nozzles changes rapidly.