Study On The Structure Of The Nozzle Of Ultra High-Pressure Abrasive Waterjet

The high pressure water jet cutting is an important application of the high pressure water jet. As a cold cutting technology,it has no cutting thermal deformation and cutting materials unique advantages range compared with the traditional cutting methods, and has been developed rapidly in various industries. The nozzle is an important part and forming water jet component in the high pressure water jet equipment.The jet flow field in the abrasive nozzle is quite complicated, and yet cannot be described accurately with mathematical method currently. It is necessary to study the jet flow fields and structure of the nozzle.In the paper ,a mathematical model of the pre-mixing abrasive water-jet nozzle with Cone and cylinder structure was established. The liquid-solid flow field of the cone nozzle with the cylinder section of the pre-mixing abrasive water-jet was simulated by the software FLUENT.The result shows that the axial velocity of solid-liquid two-phase decreased gradually from center to the wall in the nozzle exit. Particles are always accelerated in the nozzle until the exit of it. The nozzles with different length-diameter ratio are simulated and rusult shows that there be the best length-diameter ratio about 7.5 for the best cutting ability.The two-dimensional jet model for the post-mixing abrasive waterjet cutting nozzle was established. And the processes of jet flow in the nozzle is simulated by VOF transient model.Changed the mixed cavity common structure with unilateral sand inlet into symmetry double sand inlets, modeled the changed mixing chamber and then simulated the jet flow field in the mixing chamber with different length and diameter.Finally, the abrasives mixing with water jet forming the abrasive waterjet process be analysed theoretically in this paper. The relationship function for the velocity of abrasive and water jet be derived from momentum equations.The function for the relation abrasive waterjet energy with abrasive mass load ratio have been derived The best mass load ratio for maximum cutting energy of abrasive waterjet have been gotten theoretically .Eventually the achievement and shortcoming in this paper were summed up. At the same time, the author took an outlook for the future research. The results of the paper will present useful tool for the designing and optimization of the configuration of high pressure waterjet cutting nozzles.