Numerical analysis of the transition behavior and physical field of ultrasonic-assisted MIG welding droplet

Based on FLUENT software, the VOF model was selected to numerically simulate the transfer behavior of ultrasonic-assisted MIG welding droplet under the effect of gravity, surface tension, electromagnetic force and plasma flow force. The influence of ultrasonic vibration on the necking radius of the plasma flow transfer of conventional MIG welding droplets is analyzed, and the effects of ultrasonic vibration transmission and radiation on the internal pressure, vector and the entire calculated flow field of the droplet are explored. The results of comparison with conventional MIG welding show that ultrasonic vibration causes rapid necking of droplet, the necking radius decreases and the plasma flow force increases, which promotes the transfer process of droplet; the internal dynamic pressure of the droplet increases and the absolute pressure in the flow field decreases. To verify the accuracy of the simulation results, welding tests were carried out, and the droplet transfer process was filmed by high-speed camera equipment and the droplet size was obtained by image processing method, so as to effectively and quantitatively verify the accuracy of the simulation results. The comparison results show that the simulation results are in good agreement with the experimental results, and the mathematical model of the droplet transfer is reasonable.