Study on Radical Characteristics of Methane Laminar Premixed Flame Based on Hyperspectral Technology
WANG Yan1, 2, 3, WANG Bao-rui1, 2, 3*, WANG Yue1, 2, 3
1. Innovation Academy for Light-duty Gas Turbine, Chinese Academy of Sciences, Beijing 100190, China
2. Advanced Gas Turbine Laboratory, Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing 100190, China
3. University of Chinese Academy of Sciences, Beijing 100049, China
Abstract：Hyperspectral technology provides spatial and spectral dimension information. Meanwhile, the experimental technology and calculation method based on the traditional blackbody model is not suitable for the radiation characteristics of methane flame. The Hyperspectral Information of free radicals in the flame reflects many aspects of combustion characteristics, such as flame structure and component concentration distribution, which can provide a basis for improving the combustion model. This paper studied the spatial and spectral characteristics of free radicals in premixed methane flames by Hyperspectral techniques at different equivalence ratios and flow rates. The study of different equivalence ratios shows that with the increase of equivalence ratios, the radiation intensity of CH* and C*2 radicals in the center of the flame increases first and then decreases. In contrast, the average radiation intensity of CH* and C*2 radicals in the combustion region increases all the time. The point in the center of flame can represent the local combustion state. While the average radiation intensity in the combustion region represents the overall combustion state, such as heat release rate, this paper gives the different trends of the two methods quantitatively. The radiation intensity of CH* radical in the center of flame reaches the peak when the equivalence ratio is 1.01, while the radiation intensity of C*2 radical reaches the peak when the equivalence ratio is 1.12. The radiation peak of the two radicals can be used as the intensity criterion and stability of the reaction in combustion. Equivalence ratio can be expressed by the C*2 to CH* radiation intensity ratio. This paper corrected the linear relationship between C*2/CH* and equivalence ratio. It is proposed that the ratio of average radiation intensity of C*2 and CH* in the combustion zone should be used. The quadratic relationship between the ratio and equivalence ratio is also proposed. The cloud image of C*2/CH* in the combustion area is generated by hyperspectral technology, and the detailed spatial information is obtained. When the equivalence ratio is greater than 1, an obvious transition zone is found near the flame surface for the first time, which shows the advantages of hyperspectral technology. The study of different flow rates with a constant equivalence ratio shows that the flame height increases with the flow rate increase, while the concentration distribution of free radicals at the top and center of the flame does not change. It reveals that the characteristic time of a flow is far less than that of chemical reaction under experimental conditions, so the chemical reaction process is not affected. In this paper, hyperspectral technology is used to identify a variety of free radicals in the flame. The radiation characteristics of free radicals in methane laminar premixed flame and its variation trend with different equivalence ratios and flow rates are studied, which is of great significance for applying hyperspectral technology to study methane combustion characteristics and verify the reaction mechanism of methane combustion phenomenon.
王 岩，王宝瑞，王 岳. 基于高光谱技术的甲烷层流预混火焰自由基特性研究[J]. 光谱学与光谱分析, 2022, 42(08): 2403-2410.
WANG Yan, WANG Bao-rui, WANG Yue. Study on Radical Characteristics of Methane Laminar Premixed Flame Based on Hyperspectral Technology. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2022, 42(08): 2403-2410.
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