Many studies have examined the stoichiometric lengths of laminar gas jet diffusion flames. However, these have emphasized normal flames of undiluted fuel burning in air. Many questions remain about the effects of fuel dilution, oxygen-enhanced combustion, and inverse flames. Thus, the stoichiometric lengths of 287 normal and inverse gas jet flames are measured for a broad range of nitrogen dilution. The fuels are methane and propane and the ambient pressure is atmospheric. Nitrogen addition to the fuel and/or oxidizer is found to increase the stoichiometric lengths of both normal and inverse diffusion flames, but this effect is small at high reactant mole fraction. This counters previous assertions that inert addition to the fuel stream has a negligible effect on the lengths of normal diffusion flames. The analytical model of Roper is extended to these conditions by specifying the characteristic diffusivity to be the mean diffusivity of the fuel and oxidizer into stoichiometric products and a characteristic temperature that scales with the adiabatic flame temperature and the ambient temperature. The extended model correlates the measured lengths of normal and inverse flames with coefficients of determination of 0.87 for methane and 0.97 for propane.

许多研究已经检查了层状气体射流扩散火焰的化学计量长度。但是，这些都强调了未稀释燃料在空气中燃烧的正常火焰。关于燃料稀释，氧气增强燃烧和逆火焰的影响，仍然存在许多问题。因此，对于宽范围的氮气稀释，可测量287正向和反向气体喷射火焰的化学计量长度。燃料为甲烷和丙烷，环境压力为大气压。已发现向燃料和/或氧化剂中添加氮会增加正向和反向扩散火焰的化学计量长度，但是在高反应物摩尔分数下，这种影响很小。这与先前的说法相反，即燃料流中惰性添加对正常扩散火焰的长度影响可忽略不计。Roper的分析模型通过将特征扩散率指定为燃料和氧化剂在化学计量产品中的平均扩散率以及特征温度随绝热火焰温度和环境温度成比例变化而扩展到这些条件。扩展模型将测量到的正向和反向火焰长度与甲烷的测定系数0.87和丙烷的测定系数相关联。