Numerical study on flow characteristics and impact erosion in ultrasonic assisted waterjet machining

A 3D numerical model was established to study the flow field characteristics and particle erosion in ultrasonic vibration-assisted abrasive waterjet machining by using computational fluid dynamics. The vibration of target is realized by using user-defined functions and dynamic meshing. The trajectories of abrasive particles dispersed in fluid flow are calculated by employing discrete phase model. The material removal on impacted surface was considered by an erosion rate model. The results indicated that the erosion rate at center area of impacted zone is lower than that at peripheral area, which is owing to the influence of stagnation zone. The variation of pressure value at the impacted surface is related to the vibrating movement of workpiece. Due to the weakening of stagnation effect, the pressure value decreases with a reduction of impact angle. Moreover, it was found that the erosion rate induced by particle impact on target surface is increased when vibration is applied. The influence of ultrasonic vibration on erosion rate is more significant at lower impact angle.