Reduction of plug flows in an abrasive supply tube for abrasive injection jets by using branch tubes

An Abrasive Injection Jet (AIJ) often suffers from reduced machining accuracy due to pulsations that occur when the abrasive supply rate is increased. These pulsations arise from the abrasive plug flows formed within the abrasive supply tube, and suppressing them essential for achieving precise machining. In this study, a branch tube was introduced into the abrasive supply line to reduce the formation of plug flows. The effects of abrasive supply mass flow rate and, the branch tube length on, the occurrence frequency of plug flows were investigated through flow visulazation by using a high-speed camera. Abrasive plug flows, which result in large fluctuations in abrasive concentration, were observed upstream of the branch point. These plug flows collapsed at the branching point, and a more dispersed flow with reduced abrasive concentration fluctuations was maintained downstream. Under all tested conditions, the frequency of abrasive plug flows was significantly reduced downstream of the branch tube.