氨气/氢气/氮气-空气预混火焰中热释放区和预热区厚度表征与测量

Addressing the unclear characterization methods for the heat release zone and preheat zone of hydrogcn-ammonia flames, a onc-dimcnsional propagating flame Simulation approach using CHEMKIN Software is employed, in conjunction with experimental measurements from laser-induced fluorescence diagnostics of NH and NH3, to investigate potential markers for flame structure in ammonia/hydrogen/nitrogen-air mixtures. A systematic comparison is conductcd to evaluate the effectiveness of various markers in characterizing the spatial distribution of the heat release rate, the thickness of the heat rclcasc zonc, and the thickness of the preheat zone under different ammonia Cracking ratios and equivalence ratios. The results show that under lean combustion conditions, the normalized concentration of NH exhibits a good spatial correlation with the distribution of heat release rate, while the normalized concentration produet of NH2 and NO consistently correlated well with the heat release rate profilc across all working conditions. The normalized concentration of NH accurately represented the location of the heat release rate peak, and the normalized concentration produet of NH2 and NO serves as a more effective indicator for the thickness of the heat release zonc. The local minimum location of several normalized concentration sums was proposed as markers for the preheat zone leading edge. The normalized concentration sum of NH3 and NH could represent approximately 30% of the preheat zone thickness, whereas the normalized concentration sum of NH3 and NO could rcach up to 60%. Laser induced fluorescence diagnostic results of NH and NH3 further confirmed the experimental feasibility of these markers. Combining experimental results with simulation-revised outcomes, the normalized concentration of NH can be utilized for aecurate calculation of the heat release zone, while the sum of the normalized concentrations of NH3 and NH allows for precise determination of the thicknesses of both the heat release zone and the preheat zone. The findings provide useful guidance for flamc strueture identification in hydrogen-ammonia turbulent flamcs.