Measurement of CO concentration in flat flame based on mid-infrared absorption spectroscopy
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摘要: CO是碳氢化合物燃烧的主要产物之一,准确测量超燃冲压发动机出口的CO浓度是评估碳氢燃料燃烧效率的重要依据。中红外波段的CO谱线相较近红外而言,具有吸收更强、谱线丰富且谱线对相对孤立、不受其他气体干扰等明显优势。本文基于中红外吸收光谱技术,计算研究了CO中红外光谱特性,选择了适用于高温流场CO测量的特征谱线,设计并搭建了高温流场CO浓度检测系统,开展了气体池浓度标定和不同当量比下平面火焰CO测量验证,实现了某超燃冲压发动机出口高温流场CO测量,反映了航空煤油燃烧过程中CO浓度和温度的变化情况,为超燃冲压发动机的燃烧和流动机理研究提供了有力的研究手段和丰富的实验数据。Abstract: CO is one of the main products of hydrocarbon combustion. Accurate measurement of CO concentration at the scramjet outlet is an important basis for evaluating the combustion efficiency of the hydrocarbon fuel. Compared with the near infrared band, the CO absorption spectrum in the mid infrared band has the advantages of stronger absorption, rich spectral lines, relatively isolated spectral lines and no interference from other gases. Based on the mid infrared absorption spectrum technology, this paper studies the mid infrared spectrum characteristics of CO, selects the characteristic spectrum which is suitable for the measurement of CO in the high temperature flow field, designs and builds the CO concentration detection system in the high temperature flow field, carries out the CO measurement verification under different equivalence ratios of the plane flame, realizes the CO measurement of the high temperature flow field at the exit of a scramjet, and reflects the changes of concentration and temperature of CO during the combustion of aviation kerosene, thus providing powerful research means and abundant experimental data for the study of combustion and flow mechanism of the scramjet.
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Key words:
- mid-infrared absorption spectroscopy /
- TDLAS /
- CO /
- flat flame /
- scramjet
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表 1 候选谱线参数
Table 1. The parameters of candidate lines
Spectral
pairCenter
frequency
/cm-1Line strength
/(10-20 cm-1·
(mol·cm-2)-1)Low state-
energy
/cm-1Temperature
/Kpair3 2059.9147
2060.332213.40
2.75806.38280
2543.056701300 pair4 2064.3969
2064.583913.90
2.71729.67740
2489.783101300 pair3 2059.9147
2060.332210.10
3.51806.38280
2543.056701800 pair4 2064.3969
2064.583910.20
3.41729.67740
2489.783101800 表 2 不同工况下CO温度测量结果
Table 2. CO temperature measurement results under different working conditions
Order Air
/(L·min-1)CH4
/(L·min-1)ϕ Tm
/KTc
/KRelative
error1 18.9 2.39 1.2 1290.2 1237 4.3% 2 18.8 2.55 1.3 1276.7 1252 1.9% 3 18.5 2.72 1.4 1272.3 1248 1.9% -
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