Abstract
A swirling drill bit designed with an integrated vane swirler was developed to improve reverse circulation in down-the-hole hammer drilling. Its entrainment effect and influential factors were investigated by CFD simulation and experimental tests. The numerical results exhibit reasonable agreement with the experimental data, with a maximum error of 13.68%. In addition, the structural parameters of the swirler were shown to have an important effect on the reverse circulation performance of the drill bit, including the helical angle and number of spiral blades, swirler outlet area, and the flushing nozzles. The optimal parameters for the swirling drill bit without flushing nozzles include a helical angle of 60°, four spiral blades, and the area ratio of 2, while it is about 30°, 3, and 3 for the drill bit with flushing nozzles. Moreover, the entrainment ratio of the drill bit without flushing nozzles can be improved by nearly two times compared with one with flushing nozzles under the same conditions.
Highlights
Swirling flows which always lead to strong shear and centrifugal forces have been utilized in many industrial applications
Our preliminary numerical simulations verified the role of swirling flows in improving the reverse circulation within drill bits [6]
Experimental results indicate that the air mass flow rate m3, suctioned into the drill bit from the annulus between the drill bit and the borehole wall, increases almost linearly with increased blade helical angle
Summary
Swirling flows which always lead to strong shear and centrifugal forces have been utilized in many industrial applications. Yehia et al [8] completed computational fluid dynamics (CFD) simulations of working fluid behaviors in the shell and tube heat exchangers with swirlers inside. Their simulations were utilized to investigate the effect of a swirler’s geometry on heat transfer and friction loss in a shell and tube exchanger. Wen et al [9] designed ellipsoid and helical blades aiming to generate strong swirls in the natural gas flows through supersonic separators. Visualization experiments of gas-liquid two-phase swirl flows were carried out by Liu and Bai [11] in a circular straight pipe
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
