基于激光吸收光谱技术的超声速气流测量研究

Measurements of Supersonic Gas Flow Based on Laser Absorption Spectroscopy

关键词:  波长调制光谱  速度测量  温度测量  组分浓度测量  频分复用

Key words:  Wavelength modulation spectroscopy  Velocity measurement  Temperature measurement  Concentration measurement  Frequency division multiplexing

摘要:

为研究可调谐半导体激光吸收光谱测量技术在工业环境中的应用，采用波长调制光谱测量方法，对超燃直连式试验台隔离段内的超声速气流进行了测量研究。通过对7185.60cm -1 和7454.45cm -1 2条H 2 O吸收谱线的频率标定和多普勒频移测量，实现了高速气流速度的实时在线测量，测量值相对于预测值的偏差在3%以内。基于2条H 2 O吸收谱线的光谱参数和激光调制参数，建立了基于实验环境的仿真数据库。采用频分复用方法，通过迭代求解了隔离段内的温度和组分浓度，其结果相对于预测值的偏差分别在4%和12%以内。该方法不仅能够实现不同谱线的同步实时测量，而且验证了在恶劣环境下的应用效果。

Abstract:

In order to study the application of tunable diode laser absorption spectroscopy technology in the industrial environment，the supersonic gas flow in the isolator of direct-connected scramjet test facility can be studied via wavelength modulation spectroscopy technology. The real-time and on-line measurement of velocity in the high-speed gas flows can be realized after calibrating the frequency and calculating the Doppler shift of two H 2 O absorption transitions(7185.60cm -1 and 7454.45cm -1 ). The most relative error is 3% compared with the predicted value. The simulation database can be created based on the spectroscopic parameters and laser modulation parameters of two H 2 O absorption transitions. Frequency division multiplexing technology is adopted to measure gas temperature and concentration in the isolator. Compared with the predicted value，the results have a good agreement and the most relative errors are 4% and 12% respectively，which proves that the method is reasonable and reliable in the engineering application. It not only can achieve the real-time measurement at the same time，but also validates the application effects in the harsh environment.