Measurement And Simulation Of Temperature And CO₂ Concentration In A Co-flow Diffusion Flame Based On Mid-infrared Laser Absorption Spectroscopy

As a strong exothermic chemical reaction process,combustion is the most important way for human to utilize energy.We need to understand combustion process deeply in order to develop high-performance power equipments and solve the environmental pollution problems caused by fossil fuels.Laminar co-flow diffusion flame is a standard flame used in soot formation and combustion chemistry research.The distributions of flame temperature and species concentration are crucial research parameters that determines the fuel oxidation,soot formation,and combustion reaction rates.One of the most accurate in situ measurement techniques to determine flame temperature and species concentration is Tunable Diode Laser Absorption Spectroscopy（TDLAS）.Due to high sensitivity and accuracy,high reliability,and the non-intrusive nature,TDLAS technology has been widely used in gas detection of gasifiers,internal combustion engines,aero engines and other combustors.The main content of this paper is to measure the temperature and concentration of carbon dioxide in an methane laminar co-flow diffusion flame based on mid-infrared quantum cascade laser around 4.2μm in combination with Abel inversion transform.The measurement results of TDLAS are compared with CFD simulation and thermocouple measurement.The main research work is as follows:1.9 transitions in the R-branch bandhead region of the v₃ asymmetric stretching fundamental band of CO₂ at 4.2μm were selected because of following several advantages:high absorption,no absorption interference from other species,high temperature sensitivity and no absorption in air at ambient temperature.2.Fourier analysis Abel inversion method was used to improve the space resolution of measurement.Based on simulated methane co-flow diffusion flame,Fourier analysis method and Onion-Peeling method were used in the reconstruction process under noise-free and 1%noise situation.And the results showed that Fourier analysis method has excellent noise robustness.3.A laser combustion diagnostic platform including co-flow diffusion flame burner and 4.2μm mid-infrared laser was set up.A series of methane co-flow diffusion flames were measured and the experiment results were compared with thermocouple measurement and CFD simulation.