Abstract：Excited particle is a natural tracer of the chemical reaction process, but the research on the excited particle is mainly carried out under simple one-dimensional flame. In order to investigate the distributions excited state under complex conditions of chemical reaction heat quantitative characterization of rule, the methane/air coaxial jet diffusion flame test has carried out detailed ground state and excited of methane/air premixed flame burning mechanism of coaxial jet diffusion flamen and numerical simulation, analyzes the distribution characteristics of OH* and CH*, the excited state is studied on the relationship of the heat of reaction. The results showed that the chemiluminescence diagram of OH* and CH* obtained by ICCD camera and corresponding filter and the simulated results of the mole fraction distribution of OH* and CH* in the numerical were consistent. The OH* distribution was mainly divided into three combustion regions, and the CH* distribution was mainly divided into two combustion regions. The distribution of OH* and CH* in the diffusion flame presents a single peak, and the reaction heat presents a bimodal phenomenon. The changing trend of the reaction heat is similar to that of the excited state. After reaching the first peak, the exciter state gradually decreases to zero, while the reaction heat first decreases and then slowly increases to the second peak, and finally reduces to zero. In the diffusion flame, when the mass fraction of OH* and CH* in the radial direction reaches the peak, the heat of reaction also reaches the first peak. In the axial direction when the reaction rate of C2H+O=CH*+CO(R12) reaches the peak, the heat of reaction reaches the second peak. In premixed flames, with the increase of local equivalent ratio, the mass fraction of OH* and CH* increases obviously, and the distribution area is wide. When the mass fraction of OH* and CH* in the radial direction reaches the peak, the heat of reaction also reaches the peak. In the axial direction, the peaks of the four reactions rates of OH* and CH* are all in the same position, and the heat of reaction also reaches the maximum. The reaction rates of CH+O2=OH*+CO(R1) and C2H+O=CH*+CO(R12) are faster than that of H+O+M=OH*+M(R2) and C2H+O2=CH*+CO2(R11).
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