Scaling laws and numerical modelling of the laser direct energy deposition

A computational framework that can be easily implemented into a two-phase flow model has been developed for DED (direction energy deposition) process. The information on the in-flight powder stream is treated by an analytical model and regarded as input to the cladding model. The cladding model utilizes Computational Fluid Dynamics (CFD) technique with the volume of fraction (VOF) method, which considers interfacial dynamics and interaction with the powder stream. Furthermore, we have applied Buckingham π theorem to develop scaling laws for the geometry of the final track. In contrast with the dimensional empirical models proposed in the previous studies, the dimensionless laws in this study can largely match the trends of measured data with noticeable variations of working conditions collected from several different studies. The dimensionless cladding width is dominated by the dimensionless laser power with a positive correlation. The increase in dimensionless laser power and powder mass flow rate usually results in a greater value of the dimensionless cladding height, but this trend could become opposite when the values of catchment and energy efficiencies are close to 100%. A threshold that dilution suddenly goes up has also been provided and validated based on the dimensionless parameters. This study provides a reliable numerical model and scaling laws with sufficient generality. The processing window has also been carried out with constraints of dilution and contact angle, bringing design guidelines to the related industries.