摘要
研究了飞秒激光诱导化学发光测速技术,在氮气中加入少量甲烷,利用飞秒激光诱导其产生化学反应,并生成信号强度强,发光持续时间长的氰基荧光信号,进而实现高信噪比、高精度、宽范围的速度测量。实验发现,改变甲烷的浓度可以改变氰基荧光信号的强度和持续时间,浓度越低荧光信号持续时间越长。在甲烷浓度为500 ppm的实验条件下,可以得到测速下限为0.23 m/s。进一步降低甲烷浓度可以获得更低的测速下限。此外,实验评估了激光能量和延迟时间对测速精度的影响。本工作极大拓展了飞秒激光分子标记测速的应用范围,在航空航天领域具有很大的应用潜力。
Femtosecond laser molecular tagging velocimetry technology is the most commonly used noninvasive velocity measurement method.Traditional nitrogen-based molecular tagging velocimetry has a weak signal,a poor signal-to-noise ratio,and a small dynamic range of velocity measurement,which limits its application,especially in low-speed flow field.This paper mainly researches the femtosecond laser-induced chemiluminescence velocimetry technology.Femtosecond laser is introduced to interact with methane/nitrogen flow field,and generate a cyano fluorescence with strong signal intensity and long luminous duration,thus achieving a high signal-to-noise ratio,high precision and wide range velocity measurement.The experimental results show that by changing the concentration of methane,we can adjust the intensity and duration of the cyano fluorescence signal.The lower the concentration,the longer the cyano fluorescence signal lasts.In velocity measurement,it is necessary to comprehensively consider the fluorescence intensity and fluorescence duration required for velocity measurement,and select the appropriate methane concentration to achieve the best velocity measurement effect.This paper also explores the range of the velocity measurement of this method.The method has no upper limit,but the actual measurement upper limit is mainly affected by the time resolution of the hardware of the delay triggering device,the spatial resolution of the imaging system and the minimum gate width of the camera.There is a lower limit of this method.At a concentration of 500 ppm,the fluorescence signal intensity with a signal-to-noise ratio of 8 can still be obtained at 120μs after the laser radiation.The minimum resolvable displacement of the imaging system in this experiment is 27μm,and the lower limit under this experimental condition is 0.23 m/s.A lower limit can be obtained by further reducing the methane concentration.In addition,the influence of the laser energy and delay time on the speed measurement accuracy was evaluated through exper
作者
李明
高强
陈爽
李博
LI Ming;GAO Qiang;CHEN Shuang;LI Bo(State Key Laboratory of Engines,School of Mechanical Engineering,Tianjin University,Tianjin 300072,China;China Aerodynamic Research and Development Center,Mianyang,Sichuan 621000,China)
出处
《光子学报》
EI
CAS
CSCD
北大核心
2022年第3期312-320,共9页
Acta Photonica Sinica
基金
国家自然科学基金(Nos.51806149,91741205)。
关键词
飞秒激光
激光诱导荧光
化学发光
分子标记
速度场测量
Femtosecond laser
Laser-induced fluorescence
Chemiluminescence
Molecular tagging velocity
Velocity measurement
