为了研究切向气流对激光毁伤低慢小目标的影响, 采用仿真分析和实验相结合的方法研究了在激光辐照典型低慢小目标材料尼龙66过程中切向气流对激光烧蚀作用的影响。建立了激光烧蚀尼龙的简化物理模型, 利用红外热像仪分别研究了1.5 s和4 s两个时刻激光辐照下尼龙材料的温度场分布和烧蚀形貌, 并与无气流条件下的结果进行对比。实验表明, 切向气流对激光烧蚀尼龙材料过程的影响主要分两个阶段, 在辐照前段时间切向气流减缓了激光辐照下尼龙66材料的温升, 抑制了激光对尼龙材料的烧蚀作用; 但随着温度的升高, 热分解产物增多使激光屏蔽作用增强, 切向气流减轻了目标材料表面热分解产物对激光的衰减, 并为尼龙材料的氧化烧蚀提供更多氧气, 促进了烧蚀作用。最后对切向气流下激光烧蚀尼龙的过程进行了ANSYS仿真, 实验结果和仿真结果基本一致, 从而验证了理论的可靠性。

To study the influence of tangential flow on laser damage of slow small targets, a research on the effect of tangential airflow on laser ablation in the process of laser irradiation on a typical low slow small target material of nylon 66 was achieved experimentally and in simulation. The physical model of laser ablation on nylon 66 was established. Based on the model, the temperature field distribution and ablation morphology of nylon materials for 4 s and 1.5 s laser irradiation with and without tangential airflow recorded by a thermal infrared imager were analyzed. The experimental results show that the effect of tangential airflow on the process of laser ablation of nylon 66 is divided into two main stages: in the irradiation early stage, the tangential airflow slows down the thermal increase of nylon 66 materials under laser irradiation, thus restraining the laser ablation of nylon material; However, with the rise of temperature, the increase of the thermal decomposition products leads to laser shielding effect enhancement, thus the tangential flow reduces the attenuation of thermal decomposition products on the surface of target materials to laser and can provide more oxygen for ablation of nylon material. Finally, the process of laser ablation on nylon was simulated by ANSYS. The simulation results are in good agreement with the experimental results, which verifies the reliability of the theory.