Numerical model of laser energy attenuation due to interaction of the laser beam with stream of powder particles in Direct Energy Deposition

In laser direct energy deposition (L-DED), interactions between laser beam and powder particles significantly affect the laser-induced melt pool in the substrate. This study introduces a novel laser energy attenuation model, addressing absorption and reflection of laser energy by powder particles. The model calculates attenuated laser beam intensity profiles in the focal spot and incorporates them into a high-fidelity thermo-fluid model for L-DED. This comprehensive model considers multiple physical phenomena, including temperature and angle-dependent absorption, powder particle stream, particle-fluid interactions, temperature-dependent properties, buoyancy effects, thermal expansion, phase transitions, evaporation, solidification, and Marangoni flow driven by temperature and element-dependent surface tension. The total attenuated laser power , as well as the attenuated beam intensity profiles are determined for both circular and square uniform laser beams, examining their impacts on melt pool behavior. Comparisons between numerical and experimental fusion zone morphologies reveal that neglecting laser energy attenuation results in significant deviations in fusion zone dimensions, underscoring the importance of incorporating laser energy attenuation in L-DED models.