Laser coupling in waterjets subject to jet instabilities, laser parameters, and alignment errors

Area of Science:

• * Fluid Dynamics
• * Optics
• * Laser Technology

Background:

• * Waterjet-guided laser technology is crucial for processing hard-to-cut materials and in the diamond industry.
• * High coupling accuracy and efficiency are essential for advanced material processing.
• * Understanding waterjet behavior is key to optimizing laser coupling.

Purpose of the Study:

• * To investigate the hydrodynamic behavior of axisymmetric waterjets.
• * To analyze the impact of waterjet profiles on laser coupling efficiency.
• * To optimize the design of coupling units and alignment strategies for waterjet-guided lasers.

Main Methods:

• * Employed a two-phase flow k-epsilon algorithm to simulate waterjet behavior.
• * Utilized the Coupled Level Set and Volume of Fluid method for interface tracking.
• * Modeled laser electric field distributions using wave equations and the Finite Element Method.

Main Results:

• * Cavity growth was found to increase the water-air interface and enhance coupling efficiency.
• * Two types of waterjets were identified: constricted and non-constricted.
• * Constricted waterjets, detached from the nozzle wall, demonstrated significantly higher laser coupling efficiency.

Conclusions:

• * Constricted waterjets are preferable for guiding laser beams, leading to improved coupling efficiency.
• * Analysis of Numerical Aperture, wavelengths, and alignment errors aids in optimizing coupling unit design.
• * Findings provide strategies for enhancing waterjet-guided laser processing performance.