高压环境下1.58μm波段CO_2吸收光谱特性分析

The analysis of CO_2 absorption spectrum characteristics near 1.58μm at high pressures

高压气体吸收光谱特性的研究是可调谐半导体激光吸收光谱技术应用于爆轰发动机等高压燃烧环境的重要基础．为了解气体吸收光谱随压力的变化规律特别是在高压下的吸收光谱特性，本文以CO2为气体介质对其在高压环境下近红外波段1．58μm处的吸收光谱进行了理论分析与试验研究，并给出一种高压气体浓度的计算方法．在1-10．13×10^5Pa压力环境下，对1．58μm处CO2吸收光谱进行了数值模拟，搭建了高压环境气体在线测量试验系统，对CO2在波段1578．1-1579．7nm的吸收光谱进行了试验测量．利用线性回归拟合将试验所得光谱吸收率与模拟吸收率进行对比，对高压环境下气体浓度进行了计算．结果表明，试验所得吸收光谱与数值模拟结果相吻合，1-10．13×10^5Pa压力环境下利用线性拟合寻优法计算气体浓度最大误差为5．5％，平均误差2．6％．

The study of gas spectrum characteristics at high pressure is the foundation for tunable diode absorption spectroscopy technique used in pulsed detonation engines and other high-pressure combustion environments. To understand variations of gas spectrum charac- teristics with pressure, especially the absorption spectrum characteristics at high pressures, gas absorption spectrum characteristics at high pressure are studied by tunable diode laser absorption spectroscopy in this paper, a method to calculate gas concentration at high pressure is also presented. Within a pressure range of 1-10.13×10^5 Pa, CO2 absorption spectrum in a near-infrared band of 1.58μm is simulated. Gas online measurement at high pressure is set up. The CO2 absorption spectrum is measured by a direct absorption method near 1578.0-1579.7 nm. The concentration at high-pressure environment is calculated by linear fitting method and compared with theoretical absorption spectrum. The results show that the absorption spectrum obtained experimentally is in good agreement with simulations result. In high-pressure environment, maximum error of linear fitting method to calculate gas concentration at high pressure is 5.5%, and the average error is 2.6%.