Performance Analysis and Optimization of a Pulse Jet Drilling Tool with an Impeller-Type Bottom Hole Disc Valve

To further improve drilling efficiency,a bottom-hole pulse jet drilling tool with a disc valve driven by a small hydrodynamic impeller was designed based on the good performance of a bottom-hole asymmetric flow field for cuttings cleaning and auxiliary rock breaking. Performance was optimized in the hydrodynamic impeller and jetting tool through numerical simulation and experiments. The numerical simulation for fluid around impeller was carried out by using the computational fluid dynamics software, Pumplinx, in full operational conditions. The response relationships among impeller rotary speed, resistance torque and axial force were summarized by analyzing the pressure, velocity and turbulent kinetic energy distribution of internal flow fields. The inlet flow field and hydrodynamic performance of impellers were improved while the axial force was partially eliminated by setting a guide block at the inlet of jet tools, performing smoothing treatment on blade hubs and selecting appropriate blade angle. Simulation results showed that the resistance torque of natural load on impeller can be increased from 1.07 N·m to 3.93 N·m initially at the rotary speed of 75 r/min. Research results indicated that the optimal measures could improve the pulse performance of impeller-type bottom hole disc valve in pulse jet tools, with significant optimization results.