高压水-气缩流传导大功率激光加工多场耦合机理与关键技术研究

Compared with traditional short-pulse laser processing technology, water-guided laser processing technology has the advantages of smaller thermal damage, smaller taper and greater depth, cleaner surface etc., so it can be used for precision machining of refractory materials such as superalloy and composite materials. However, the existing technologies have two key problems of low laser coupling power and poor process reliability, which seriously affect laser processing efficiency and workpiece processing quality. Based on this situation, a water-gas-conducted high-power laser processing method is innovatively proposed . It guides high-power laser into the millimeter-level water jet. Through gas-coating, laminar shrinkage and total reflection, the high-energy laser is coupled into the hundred-micron level laminar water jet to achieve high-efficient and reliable processing of high-power density laser on a variety of intractable materials. In this project, the multi-field coupling effect mechanism of the water-gas-laser is explored with the methods of theoretical modeling, simulation analysis and experimental study; the compression effect of airflow on the diameter of water jet will be studied to find the conditions of high-pressure airflow covering waterflow to keep laminar flow and the efficient coupling conditions of laser total reflection; moreover, the impact of physical processes such as formation and movement of plasma on the material removal performance will be analyzed under high-pressure water vapor scour. In the end, a coupling experiment device will be designed, and this technology will be verified with aviation superalloy and composites. The results of the study will provide theoretical guidance and technical support for the efficient and reliable processing of large-thickness and hard-to-process materials in aviation and civil fields.

水导激光加工技术相比短脉冲激光加工具有热影响小、锥度小、深度能力强、加工表面清洁等优势，可以对高温合金、复合材料等难加工材料进行精密加工，但现有技术存在激光耦合功率低和工艺可靠性差两个关键难题，严重影响激光加工效率与质量。基于此，本项目创新性地提出了一种高压水-气缩流传导大功率激光加工方法。其将大功率激光导入毫米级同轴水柱，经气体包覆、层流缩水和全反射导光，将高能激光耦合进百微米级层流水柱中，实现高功率密度激光对难加工材料高效、可靠加工。本项目拟采用理论建模、仿真分析与试验研究相结合的方法，探究水-气-激光多场耦合效应作用机理，研究气流对水射流直径的压缩效应，寻求高压气流包覆水流保持层流条件以及激光全反射高效耦合条件；揭示高压水气冲刷下等离子体形成、移动等物理过程对材料去除性能的影响；设计耦合试验装置并对难加工材料进行试验验证，为航空及民用大厚度难加工材料高效、可靠加工提供理论与技术支持。

本项目提出了一种高压水-气缩流传导大功率激光加工方法。采用理论建模、仿真分析与试验研究相结合的方法，探究了水-气-激光多场耦合效应作用机理，研究了气体包覆、层流缩水和全反射导光机制，并通过试验验证了本方法的可行性，其研究成果为水导激光大功率、高可靠性加工奠定了理论基础，为水导激光在航空及民用大厚度难加工材料高效、可靠加工方面提供理论与技术支持，具有较强的创新性与前瞻性。.本项目采用理论建模/流体仿真/光学仿真等手段，建立了水气缩流传光模型及多场耦合仿真分析平台（GAMBIT-FLUENT-ZEMAX），得到了水气缩流流动分布状态，分析了层流全反射特性、边界条件及能量损失成因；分析了水导激光材料去除特性，并阐明了去除材料阈值与水柱能量密度的对应关系；利用流体仿真得到的水-气层流界面结构，进行了激光耦合层流全反射仿真分析，并将传统水导激光与水-气缩流导光方法进行了抗扰动能力对比分析，验证了大功率传光可靠性；利用自主搭建的试验平台，完成了水气缩流方案工艺的可行性验证，并进行了多种材料切割能力测试；深入研究了针对难加工复合材料的水导激光加工工艺，得到了厚板材料的加工工艺方法。试验结果显示，本方法可以实现多种难加工材料的高质量打孔与切割加工。相比干式激光切割工艺，水-气缩流导光切割工艺加工锥度更小，加工表面质量更高，深度能力更强。为水-气缩流导光技术进一步发展提供技术支持。