不同工作模式下激光熔化沉积过程熔池演变数值研究

There are two laser modes in laser melting deposition process, continuous-wave (CW) and pulse-wave(PW). Based on Fluent, a three-dimensional symmetrical numerical model is established for the transient motion and heat and mass transfer of the molten pool. By solving the volume of fluid (VOF) continuous equation, free surface of deposition layer is trayed, and the evolution process of the molten pool formation and the variation law of the upper surface wave motion under different laser working modes are analyzed. The size of the molten pool, the maximum flow velocity and the maximum temperature are compared. The results show that the simulation results are in good agreement with the experimental results; the middle part of the upper surface of the molten pool will undergo the fluctuation process of depression and bulge under the two laser modes. The flow velocity in the molten pool under CW mode is more stable than that under PW mode, and the flow in the later stage is quasi steady, while the pool formation process will be repeated in PW mode. The maximum flow velocity and maximum temperature in the molten pool change periodically under PW mode. Pulsed laser increases the fluctuation of the upper surface of the molten pool, and the fluctuation amplitude of the upper surface is 1.8 times of that of CW mode. The larger fluctuation of molten pool can balance the unmelted slag particles well.