通过具有高灵敏度、 非侵入式等特性的可调谐二极管激光吸收光谱技术对发动机气缸工作过程等高温高压燃烧环境进行实时在线检测, 是了解其内部燃烧过程进而研发高效发动机的重要手段之一。 作为一种重要的温室气体和化石燃料燃烧的主要产物, 二氧化碳对于了解燃烧过程具有重要的意义。 为了寻找一种能够对高温高压燃烧过程中的二氧化碳浓度进行快速检测的方法, 利用工作在室温条件下的近红外可调谐二极管激光器作为光源, 以二氧化碳位于5 006.140 cm-1处的跃迁作为传感谱线, 结合固定波长的吸收光谱调制技术, 通过该CO2谱线的一次谐波归一化的二次谐波信号峰值实现对高温高压环境中CO2浓度测量, 建立了一种可用于高温高压环境下的组份浓度的测量方法, 通过实验验证得出该方法在5 atm压力、 500 K温度下和10 atm压力、 1 000 K温度下对于CO2浓度测量的平均标准偏差为3.99%; 另外还对实验中所得CO2直接吸收及二次谐波信号进行了分析, 得到了其吸收光谱在高温高压环境下的特性。

The present research was planned to develop a method for species concentration measurements under high temperature and pressure environments. The characteristics of CO2 spectrum at high temperature and pressure were studied at first. Based on the research above, tunable diode-laser absorption of CO2 near 2.0 μm incorporating fixed-wavelength modulation spectroscopy with second-harmonic detection was used to provide a method for sensitive and accurate measurements of gas temperature and CO2 concentration at high temperature and pressure. Measurements were performed in a well-controlled high temperature and pressure static cell. The results show that the average error of the CO2 concentration measurements at 5 atm, 500 K and 10 atm, 1000 K is 4.49%. All measurements show the accuracy and potential utility of the method for high temperature and pressure diagnostics.