The Influence of the Annular Nozzle's Structural Parameters on Powder Stream Convergence for Laser-Directed Energy...

Area of Science:

• Materials Science and Engineering
• Additive Manufacturing
• Computational Fluid Dynamics

Background:

• Laser-directed energy deposition (L-DED) is crucial in advanced manufacturing.
• Powder feeding nozzle convergence directly impacts L-DED part accuracy and quality.
• A comprehensive optimization scheme for annular nozzle powder feeding structures is lacking in current literature.

Purpose of the Study:

• To investigate the influence of internal annular nozzle structures on powder convergence.
• To establish a basis for optimizing annular nozzle design for improved powder convergence in L-DED.

Main Methods:

• Finite element analysis models of annular nozzles were developed.
• The Lagrangian-Eulerian method was employed to simulate powder flow dynamics.
• Parametric studies included varying outlet shapes, inclination angles, outlet gaps, inlet shapes, particle size, and gas flow rates.

Main Results:

• Parallel outlet shapes are optimal for annular nozzles.
• Decreasing inclination angle and outlet gap reduces powder stream waist diameter.
• Reduced particle size and carrier gas rate improve powder convergence, achieving a 1.42 mm waist diameter; increased laser shielding gas rate lowers convergence position.

Conclusions:

• Specific geometric parameters (17° inclination, 0.5 mm gap) can reduce powder stream waist diameter by 49%.
• Particle size, carrier gas, and shielding gas rates are critical for controlling powder convergence.
• The study provides essential data for designing high-convergence annular nozzles for L-DED processes.