Investigation On The Stability Of Capillary Waterjet Influenced By Cavitation

With the development of technology,products are miniaturized and miniaturized.This trend has driven the continuous improvement of processing technology.The applications of laser capillary waterjet,needleless injector,high pressure water cutter,hydroentangling process etc.are concrete manifestations that must be guaranteed with a long breakup length.The stability of jet are influenced by a large number of parameters,the paper study on effect of cavitation on waterjet.Due to the very small time and length scales involved in high-speed flow through micro-nozzles in high pressure,experimental observation of the jet formation and fluid flow through the nozzles is cumbersome if not impossible.Computational fluid dynamics(CFD)simulation,on the other hand,can improve the understanding of waterjet formation and fluid flow process under such conditions.the simulation results of cavitation are compared with cavitation-free whereby we can observe the flow field in micro nozzle and discuss the influence of stability of waterjet.The paper models flow behavior of cavitation and cavitation-free with different Reynolds number in 2D space.The results show that bubbles become unsteady and grow explosively into vaporous cavity below saturated vapor pressure.Continuing growing up of cavity results in increasing of reattachment length which is more easy to envelop constricted waterjet compare with cavitation-free.Simulation of three-dimension waterjet model verifies the development of jet in two-dimension space.According to the flow characteristic of jet with considering the limited of laser round waterjet,we modeled rectangle and slot capillary waterjet,the result show that slot waterjet can also be used for guiding laser.Eventually the achievement and shortcoming in this paper were summed up.At the time,the author took an outlook for the future research.