超短激光打孔中快速相变的格子玻尔兹曼模拟

采用双重分布函数的格子玻尔兹曼模型,对单脉冲激光金属打孔过程中的快速相变传热进行研究.模型考虑了金属材料熔化后熔体的流动换热,并采用浸没移动边界方案对过程中的固液界面进行追踪.采用纯导热模型和考虑对流的换热模型计算,将结果和试验进行对比,结果表明:在激光打孔过程中熔体的流动对相变传热产生较大影响,采用考虑流动换热模型的结果与实验更接近.进而对熔化速度、熔化深度以及温度场的变化进行分析,并探讨不同激光工艺参数对相变过程的影响.模拟发现一个脉冲结束后,激光的脉宽越大,孔深越小,孔径越大,且最高温度较短脉冲激光越低.

Lattice Boltzmann Simulation of Fast Phase Change in Ultrashort Laser Drilling

Lattice Boltzmann model with double distribution function is used to study fast phase-change heat transfer in single-pulse laser metal drilling process. Flow and heat transfer of the melted metal material is considered and an immersion moving boundary scheme was used to track solid-liquid interface in the process. Pure heat conduction model and heat transfer model considering convection are used to simulate the process and the results are compared with experimental data. It shows that flow of the melted material has a great impact on phase change heat transfer during laser drilling and results with model that considers flow heat transfer are closer to experimental data. Melting rate, melting depth and temperature field distribution were analyzed, and effects of laser parameters on phase transition process were discussed. It shows that at the end of a pulse, the larger the pulse width of laser, the smaller hole depth, the larger aperture, and the lower temperature of shorter pulse laser are found.