Research on the Influence of Water-Laser Coupling Cavity and Nozzle Structure on the Flow Characteristics of Water Beam Fiber

In the water jet-guided laser processing technology, the stability and impact characteristics of water jet have an important impact on the processing quality. In order to study the influence of the structure of the water-laser coupling cavity and the nozzle on the flow characteristics of water jet, the numerical models of the flow field in the water-laser coupling cavity and the water beam fiber are established, and the distribution characteristics of the velocity and turbulent kinetic energy are simulated and analyzed. The Taguchi method is used to build a simulation model with the nozzle cylinder length, the diffusion length and the diffusion angle as design variables, and the stable length and impact force of water beam fiber as the evaluation indexes. The nozzle structure parameters are optimized based on variance analysis and signal-to-noise ratio analysis. Finally, the simulation results are verified by experiments. The results show that when the channel distribution in the water-laser coupling cavity is 8 × 8 structure, the flow velocity and turbulent kinetic energy distribution in the flow field are more uniform, and the streamline concentration at the nozzle inlet is better. The stable length of the water fiber obtained by nozzle optimization is 4% higher than that before optimization, and the impact force of water jet increases by 16.9%. The error between the experimental and simulated values of the stable length and impact force are less than 4.9%, indicating that the numerical simulation results of the water beam fiber are reliable.