Numerical simulation of ultrasound assisted powder feed flow in coaxial nozzle used in direct metal deposition process

This study investigates a hybrid gas-ultrasonic powder feed system for coaxial nozzles in Direct Metal Deposition (DMD) process. We present a coupled experimental and numerical approach to analyze the effects of ultrasonic vibration (40 kHz) on powder stream characteristics such as mass flow rate, focal plane position, and particle distribution uniformity. A numerical model was developed using the Discrete Phase Method (DPM) with empirically calibrated restitution coefficients to account for ultrasound-induced particle-wall interactions, avoiding costly structural dynamics simulations. Experimental validation was performed using a modified coaxial nozzle with integrated piezoelectric actuators to induce ultrasonic vibrations on powder feed channel. Results demonstrate that ultrasound vibrations reduces particle-wall adhesion by 10–15%, increasing mean particle velocity by 17–22%. The hybrid mode achieved an 8% higher peak powder concentration in the focal zone. The predicted focal height and diameter of the powder stream in the numerical model lies within gathered experimental data. This work provides a validated framework for optimizing ultrasonic powder delivery systems in additive manufacturing, offering significant improvements in process stability and deposition quality.