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提出一种基于有限体积法的二维数学模型,以研究20 mm厚2219铝合金板在电子束焊接过程的热传递、流体流动以及匙孔的动力学行为。采用一种能够实时跟踪匙孔深度的自适应热源模型来数值模拟电子束的加热过程。由表面张力、热毛细力、反冲压力、流体静压力以及热浮力等诱导的不同涡旋的热和质量输运作用与匙孔演变相互耦合。详细分析了一系列物理现象,包括电子束焊接过程中的匙孔钻取、塌陷、重新打开、准稳态过程、回填过程以及在此过程中的温度变化。结果表明,深度方向降低的电子束热流能减慢反冲压力的匙孔钻取速度,并促进准稳定状态的出现。在准稳定状态出现之前,匙孔会发生塌陷并加剧涡旋流体输运的复杂性。最后,所有的计算结果与实验结果进行对比,来验证数学模型的可行性。
A two-dimensional mathematical model based on finite volume method was proposed to study the heat transfer, fluid flow and keyhole dynamics of 20 mm thick 2219 aluminum alloy sheet during electron beam welding. An adaptive heat source model that can track the keyhole depth in real time is used to numerically simulate the electron beam heating process. The heat and mass transport of different vortices induced by surface tension, hot capillary force, recoil pressure, hydrostatic pressure and thermal buoyancy are coupled with the evolution of the keyhole. A series of physical phenomena has been analyzed in detail, including keyhole drilling, collapse, reopening, quasi-steady-state, backfill, and temperature changes during this process. The results show that the electron beam heat flux reduced in the depth direction can slow the keyhole drilling speed of recoil pressure and promote the quasi-steady state. Prior to the quasi-steady state, the keyhole collapses and exacerbates the complexity of the vortex fluid transport. Finally, all the calculated results are compared with the experimental results to verify the feasibility of the mathematical model.