摘要:
为了研究流场中碳纤维增强环氧树脂复合材料在激光辐照时产生的烧蚀羽烟对入射激光的屏蔽效应,通过对朗伯-比尔定律进行分析,得到了评价羽烟消光性能的平均质量消光系数的表达式,其与羽烟场浓度和激光透过率相关。采用激光诱导炽光法（LII）和激光消光法,搭建了羽烟消光性能联合诊断实验平台,使待测激光落于LII的激发光平面上,通过同步采集待测激光的透过率和LII信号,获得激发光平面上羽烟浓度场和激光消光比,得到羽烟在不同气流速度下的平均质量消光系数。实验得到气流速度为7,10,20 m/s时羽烟对1064 nm激光的归一化质量消光系数分别为2.51,1.08,1.00。实验发现,质量消光系数受到气流速度影响,当气流速度较低时质量消光系数曲线波动幅度大,且曲线均值较大；当气流速度较高时质量消光系数趋于稳定且均值较小。
Abstract:
In order to study the extinction effect of ablating soot produced by carbon fiber reinforced composite materials, which are located in an air flow field and are irradiated by laser, Laser induced incandescence (LII) and laser extinction methods are employed. Experiment is set up to diagnose the soot extinction characteristics combining these two methods. In the experiment, a laser light is set in the excitation plane of LII, then laser transmittance and LII signals are recorded synchronously to obtain the laser extinction ratio and soot concentration field. From these data, the mean mass extinction coefficients of soot are derived at a series of air flow velocities. The normalized mean mass extinction coefficient values of soot for 1064 nm laser are 2.51, 1.08, 1.00 at air flow velocities 7 m/s, 10 m/s, 20 m/s, respectively. When the air flow velocity is low, the amplitude of N curve fluctuation is big, and the mean value is big too. When the air flow velocity is high, the N curve fluctuation is slight, and the mean value is small.
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