A swirling jet from a nozzle with tangential inlets and its characteristics in breaking-up rocks

Abstract

In order to apply a swirling jet to a PDC drill bit, the nozzle performance in uenced by nozzle inlet geometric parameters and rock breaking tests under submerged conditions were studied. Numerical simulation was used to study the in uence of the nozzle structure on the swirling intensity and nozzle discharge coef cient. Simulation results indicate that spreading angle of the swirling jet is greater than that of the non-swirling jet, and the swirling intensity of the jet is strongly in uenced by the length of the nozzle body but weakly by the number of tangential inlets. Rock breaking tests were conducted to evaluate the performance of the swirling jet. It is found that the swirling jet shows a lower threshold pressure to break the rock samples and could break rock more ef ciently compared with the non-swirling jet.