Numerical Simulation Of Droplet Transfer Of Magnesium Alloy DE-GMAW

In this paper, through the analysis of characteristics of Magnesium alloy welding, according to the theory of numerical simulation of droplet transfer, and combined with the theory of fluid dynamics theory and Navier-Stokes equation, and the UDF secondary development program, the droplet transfer of DE-GMAW and GMAW welding was simulated.Firstly, according to the theory of fluid dynamic, using Fluent establish the model of droplet transfer of DE-GMAW, and combining with second development program. The current density distribution of DE-GMAW based on the current density of GMAW at the end of wire, which is GAUSS current distribution. The whole process of droplet transfer was simulated when the bypass current is 0A, 105 A, 180 A, at this time the main current is 230 A, and the drip melting bypass current under the condition of different size and transition frequency are analyzed, in addition, under the situation of different bypass current, the internal pressure of molten droplet field, the temperature field, the velocity field of droplet surface, and the distribution of current density distribution was analysed. In order to let the simulation data provide certain theoretical to the welding experiment, this paper simulates the bypass current from 0A to 180 A, each increment is 5A, and the simulation result was collated by by Origin8.0 software, the results show that the time of droplet transfer, transition frequency, droplet size change with the increasment of bypass current.Secondly, in order to compare DE-GMAW with the traditional GMAW welding method, this paper simulates the droplet transfer of Magnesium alloy DE-GMAW when the bypass current is 0A, the main road is 230 A, moreover,the traditional GMAW was simulated when the main current is 230 A, finally the simulation results show that when the welding current is 230 A, the time of droplet transfer of GMAW is 8.3ms, the droplet size is 1.15 mm, the type of droplet transfer belongs to spray transfer, the droplet shape is spherical. Under the same welding current, the time of droplet transfer of DE-GMAW is 13.6ms, the droplet shape is ellipsoid, droplet transfer type can be approximated as large droplet of transition. The tradition of GMAW welding is more faster, as a result of the addition of TIG led to the end of the wire,which lead to the flow distribution disunity.Finally, in order to verify the simulation results of accuracy, using CCD image acquisition system take the droplet transfer pictures under different bypass current in the test process, and using image processing technology to get the droplet size at different moments, the comparison of the test results and the simulation result,and calculating the rate of deviation. The final simulation results with the test image processing results are basically consistent, the numerical simulation method in a certain extent, can provide a theoretical basis for the welding tests.