激光熔池三维非稳态对流传热过程的数值模拟

建立了带有移动热源的激光熔池流体流动及传热过程三维非稳态数学模型.采用自适应网格技术离散求解动量方程,计算出了不同时刻激光熔池温度分布和速度分布.结果表明,激光熔池对流传热非稳态过程是一个预热过程,随着时间的推移,熔池最高温度不断升高,熔深和熔池半径不断增大.非稳态过程按时间先后次序分为3个阶段初始阶段(加热熔化阶段)、准稳态阶段和快速升温阶段.准稳态阶段熔池形貌、温度分布和速度分布增加幅度不大,且持续时间比另两个阶段长,说明三维准稳态模型是三维非稳态模型的较好近似.计算结果与已有的实验结果相比大体吻合.

Numerical simulation for the process of 3D transient convection and heat transfer in the molten pool

A 3D model for fluid flow and heat transfer process has been developed to predict the transient distribution of temperature and velocity of a thick solid irradiated by a moving laser.The governing equations are solved by means of a finite difference on the self adaptive grids.The results show that the unsteady state process of fluid flow and heat transfer in laser molten pool is a preheating process as the highest surface temperature,depth and radius of the molten pool increase with the scanning time.According to the sequence of time,the unsteady state process can be divided into three stages:the initial stage,the quasi state stage and the rapidly rising temperature stage.At quasi state stage,there is a little increase in the dimension and the highest surface temperature of the molten pool,the staying time is much longer than those of the other stages,which show that 3D quasi state is a good approximation to 3D unsteady state model.The calculated results are consistent with those obtained by Wang.