固定电弧脉冲TIG焊接熔池流体流动与传热模型

在浮力、电磁力和表面张力梯度共同作用下对固定电弧脉冲ＴＩＧ焊接熔池中的流体流动与传热的动态过程建立了数学模型。在控制方程组强烈耦合的情况下，将处理导热问题边界条件的附加源项法应用于处理动量边界条件，同时采用交替方向隐式迭代法及双块修正技术，使求解非稳态控制方程组的迭代收敛速度大为提高。计算结果展示了脉冲ＴＩＧ焊接过程中，随着焊接电流的周期性变化，熔池流场与热场的周期性变化规律以及熔池形成的动态发展过程。根据该模型得出的计算结果与试验测定结果吻合程度良好。

Modeling of Fluid Flow and Heat Transfer in Stationary Pulsed Current TIG Weld Pool

A computational model is presented to describe transient behavior of fluid flow and heat transfer in stationary pulsed current TIU weld pool,which considers three driving forces for weld pool convection:buoyancy force, electromagnetic force,and surface tension force at the weld pool surface.As the transient momentum equation and energy equation are mutually coupled by the momentum boundary condition,the AST(additive source term)method which concerns with the thermal energy boundary condition is extended to deal with the momentum boundary condition Furthermore,the ADI(alternation direction implicit)method and DBC(double-blocks correction)technique are employed to solve the finite difference equations.With these techniques,the convergent speed is increased.The results of numerical simulation demonstrate the transient behavior of weld pool and the periodic variation of fluid flow and heat transfer with the periodic variation of welding current in stationary pulsed current TIG weld pool.The theoretical predictions based on this model are found to be in good agreement with the experimental measurements.