激光深熔焊接过程中的光致等离子体行为特征模拟

Numerical Simulation of Behavior Characteristics of Laser Induced Plasma during Deep Penetration Laser Welding

采用Level-set方法模拟了激光深熔焊接过程中光致等离子体的动态形成过程,研究了等离子体形态、温度、孔内压强、气体流速等行为特征。结果表明:在2.2ms时刻等离子体的最高温度达到4 300K,孔内的最大压强为4×105 Pa,等离子体在小孔径向的最大流速为60m/s,最大流速位于等离子体中心处且接近孔底的位置,且等离子体沿小孔轴线方向与径向方向的流速下降。考虑等离子体对激光能量吸收比未考虑等离子体对激光能量吸收时孔内功率密度降低了12.5%。研究结果将为激光深熔焊接过程中等离子体的机理研究和模拟研究提供理论依据。

In this paper,The dynamic formation of the plasma during deep-penetration laser welding was simulated by the levelset method.The behavioral characteristics of plasma such as the morphology,temperature,hole pressure,gas flow rate are investigated in detail.The results show：At the moment of 2.2ms,the highest temperature of the plasma reached 4 300K;the maximum pressure of the keyhole rose to 4×105Pa;the maximum flow rate of the plasma in the radial direction of keyhole is60m/s,the maximum flow rate is located in the center of plasma,and it was also closed to the bottom of the keyhole,moreover,the velocity was declining along the axis and the radial direction of the keyhole.The power density in the keyhole which the plasma absorption was incorporated was12.5%lower than that the plasma absorption was not considered.The results of the research in this paper would provide a theoretical basis for the mechanism and simulation study of plasma in the process of deep-penetration laser welding.