等离子熔积成形混相瞬态场的Level-Set方法模拟

Simulation of multiphase transient field by the Level-Set approach during plasma powder deposition process

提出了一种二维等离子熔积成形瞬态模型,该模型描述了液/气界面的自由表面发展,并模拟了熔池内流体流动和传热.采用Level-Set方法处理液/气界面边界条件,考虑了熔体流动的主要驱动力———表面张力梯度、表面曲率、浮力以及工件表面的对流散热等因素.用固液相统一模型来描述固/液界面处的熔融和凝固过程,并开发了相应的软件,对高温合金K163在不同扫描速度下的熔积层表面形貌、温度场以及熔池内流场进行了模拟分析.

A 2D-transient mathematical model for plasma powder deposition shaping was developed, by which the free surface evolution of the liquid/vapor （L/V） interface was described and the fluid flow and heat transfer were simulated. The Level-Set approach was adopted to deal with the L/V interface boundary conditions, which considered surface tension gradient （the major driving forces for the melt flow）, interface curvatures, buoyancy and convection heat loss. The mixture continuum model was used for describing melting and solidification processes at the solid/liquid （S/L） interface. Moreover, the surface profile and temperature distribution of the deposition layer and fluid flow in the molten pool at different scanning speeds have been investigated based on high temperature alloy K163 powders. The experiments agree well with the simulation results.