基于最小二乘法的激光吸收光谱非均匀温度/浓度分布研究

研究了可调谐半导体激光吸收光谱技术实现非均匀温度/浓度分布测量。通过扫描多条H₂O吸收谱线，利用最小二乘算法求解非线性方程，数值模拟和实验得到沿光路方向上的两区温度和浓度分布。计算结果表明采用10条H₂O吸收谱线，计算得到温度相对模型温度的最大偏差为8.3%，浓度偏差为7.6%。通过增加扫描吸收谱线数目和减少未知数个数可以提高计算结果精度。实验测量得到高温区和低温区温度较热电偶读数偏差分别为13.8%和3.5%，数值计算结果与实验结果基本吻合。

Measurement of Nonuniform Temperature and Concentration Distribution by Absorption Spectroscopy Based on Least-Square Fitting

The measurement of nonuniform temperature and concentration distributions was investigated based on tunable diode laser absorption spectroscopy technology. Through direct scanning multiple absorption lines of H₂O, two zones for temperature and concentration distribution were achieved by solving nonlinear equations by least-square fitting from numerical and experimental studies. The numerical results show that the calculated temperature and concentration have relative errors of 8.3% and 7.6% compared to the model, respectively. The calculating accuracy can be improved by increasing the number of absorption lines and reduction in unknown numbers. Compared with the thermocouple readings, the high and low temperatures have relative errors of 13.8% and 3.5% respectively. The numerical results are in agreement with the experimental results.