CFD and ray tracing analysis of a discrete nozzle for laser metal deposition

Blown powder laser metal deposition (p-LMD) is an advanced additive manufacturing technique that creates metal components by fusing metal powder particles with a substrate using a high-power laser source. This study explores the interactions between laser energy, powder flow, and gas dynamics within a three-channel nozzle configuration for a p-LMD processes, using an innovative three-step CFD–ray tracing model. Experimental techniques, including scanning electron microscopy for powder characterisation, radiometry for emissivity calibration, Pitot tube anemometry for gas flow velocity, and particle image velocimetry for particle velocity measurements, calibrate and validate the model. Employing ray tracing, the study evaluates the consequences of reflected and scattered light on the effective laser field seen by the powder cloud during the LMD process. Significant findings include the identification of optimal gas flow rates for effective shielding of the interaction volume and the impact of varying mass flow rates on laser beam attenuation and particle heating.