Dynamics of Radiative Low-Stretch Diffusion Flames

本文对低拉伸率下气体扩散火焰的结构和熄灭行为进行了实验和理论研究。 低拉伸条件是由底部燃烧的燃料混合物排出的多孔轴对称燃烧器的非常大的半径。 研究的燃料包括甲烷、氢气、一氧化碳/氢气和一氧化碳/甲烷。 空间分辨的物种，温度和速度分布测量与激光诊断。 火焰辐射和燃烧器表面辐射也进行了检查。 相应的理论模型开发纳入窄带辐射模型。 研究内容包括五个方面：（1）实验确定拉伸率和燃料稀释量对可燃极限的影响，重点是辐射诱导消光：（2）实验探索“可燃物”的存在;（3）火焰结构的实验测绘，包括流体动力学、热、和物种分布以及来自火焰和燃烧器表面的辐射强度;（4）用详细的化学性质、传输特性和火焰/表面辐射详细模拟低拉伸扩散;（5）发展详细的辐射模型，包括光谱形式的火焰-表面相互作用和重新评价平均带参数。

This is an experimental and theoretical investigation of the structure and extinction behavior of gaseous diffusion flames at low stretch rates. The low-stretch condition is created by bottom-burning of a fuel mixture discharged from a porous axisymmetric burner of very large radius. Fuels studied include methane, hydrogen, carbon monoxide/hydrogen, and carbon monoxide/methane. Spatially resolved species, temperature, and velocity profiles are measured with laser diagnostics. Flame radiation and burner-surface radiation are also examined. Corresponding theoretical models are developed incorporating a narrowband radiation model. The study consists of five elements: (1) experimental determination of the flammability limit boundaries as functions of stretch rate and the amount of fuel dilution with emphasis on the radiation- induced extinction; (2) experimental exploration for the existence of "flamelets"; (3) experimental mapping of flame structure including hydrodynamic, thermal, and species profiles and radiation intensities from the flame and burner surface; (4) detailed modeling of low-stretch diffusion with detailed chemistry, transport properties, and flame/surface radiation; and (5) development of detailed radiation models including flame-surface interaction in a spectral manner and reevaluation of mean band parameters.