切向气流作用下激光对薄铝板辐照效应的初步研究

Preliminary study on effects of laser irradiation on thin aluminum alloy sheet in tangential flow

采用实验测量与数值模拟相结合的方法研究了切向表面气流环境中激光对薄铝板的辐照效应。实验结果表明:相同速度的氮气流和空气流中,铝板温度曲线相似,说明对于铝这种材料而言,空气流的氧化烧蚀几乎不能进行。无切向气流时,辐照过程中相同时刻铝板的温升及铝板达到的最高温度都高于氮气流和空气流情形。三种环境中,铝板中心位移的变化趋势同温度的变化趋势相同,说明激光加热产生的热应力是铝板形变的主要原因,切向气流不起主导作用。利用有限元分析软件ANSYS数值模拟了铝板温度场及形变的演化过程,分析了激光功率分布和对流换热对结果的影响,数值模拟结果同实验符合地较好。研究结果表明:在较低激光功率密度条件下,切向气流主要通过对流换热对铝板起冷却作用,尤其在激光辐照停止后的降温阶段,其作用更加明显。

Experiments and simulations were performed to study the laser irradiation effects on thin aluminum alloy sheet in different tangential flow. The temperature traces of the aluminum alloy sheet in the nitrogen flow and air flow were consistent, which indicated that the combustion effect could hardly progress. The temperature of aluminum alloy sheet without flow was higher than those in the nitrogen flow and air flow at the same time. The center displacements traces of the aluminum alloy sheet in three different gas flows kept same shape with corresponding temperature traces, which implied that the tangential flow did not play a dominant role compared with the heat distortion induced by laser heating. Moreover, a numerical model was developed, with finite element analysis software ANSYS, to simulate the process of temperature and displacement of the aluminum alloy sheet in different gas flow and analysis how the power distribution and convection heat transfer impact the results was performed. The computed results present good agreements with experiment data. The results show that the tangential flow mainly take on cooling effect when the power density of laser is not high, especially in the cooling period when the laser irradiation ends.