以解析解和數值模擬分析雷射製程之無因次參數(II)

A computational framework that can be easily implemented into a two-phase flow model has been developed for DED (wire-feeding direction energy deposition) process. Computational Fluid Dynamics (CFD) technique, including continuity, momentum, and heat transfer, volume of fraction (VOF) method have been intergrated to investigate wirefeeding type DED (direction energy deposition) process. The influence of Marangoni effect and recoil force effect on the size of final cladding geometry has been investigated through the fluid flow and heat transfer withing the melting pool. We have further utilzied the CFD results to investigate the trends of output parameters, such as cladding height, cladding width, and dilution in terms of working conditions, such as wire-feeding mass flow rate, laser power, and scanning speed. Special emphasis has been placed to explain the insensitive trends of the laser power to cladding height, the wire-feeding mass flow rate to cladding width, and the scanning speed to dilution. Besides, we have applied statistic approach over a large number of experiment data and verified the trends observed from CFD investigations. The influence of content of sulfur concentration has also been evaluated through the current CFD framework. This study provides a reliable numerical model and brings further insightful information of the interaction between the working conditions and final track geometry, which benefits the development of design guidelines to the related industries. Besides, this study investigates the evaporation phenomenon during laser welding. In contrast with previous studies adjust the evaporation coefficient to match the experimental welding geometries, the variation of metal components for alloys has also been taken into consideration by a evaporation model that deals with the Knudsen layer across the interface of melting pool. A more complete set of evaporation model in terms of continuity, momentum, and energy balance has been developed. Moreover, the Marangoni effect is found to enhance the flow mixing within the melting pool, which helps the homogeneity of pure element during the composition loss.