本生灯法结合纹影技术测量甲烷/空气层流燃烧速度及流场分析

层流燃烧速度是确定燃烧传播模型和验证化学反应机理的关键参数。搭建了本生灯实验系统和纹影实验系统用于探究甲烷预混层流燃烧特性，通过本生灯法和纹影技术测得了甲烷/氮气/空气的层流燃烧速度和火焰外部流场，并且探究了当量比及氮气掺混对层流燃烧速度和火焰外部流场的影响。研究发现，当量比对甲烷层流预混火焰燃烧特性有着重要的影响，随着当量比的增加，层流燃烧速度先增大后减小，锥形火焰高度先减小后增加，火焰外部流场开始逐渐趋于稳定；氮气掺混对层流燃烧速度起着降低的作用，且掺混的氮气越多，层流燃烧速度降低幅度越大；掺混氮气后火焰高度增加，但是火焰外部流场变得更加紊乱，难以稳定。

Measurements of laminar burning velocity and analysis of its field for the laminar premixed methane-air flames using the Bunsen burner method and schlieren technique

The laminar burning velocity is a key parameter for determining the combustion propagation model and verifying the chemical reaction mechanism. In this paper, the Bunsen burner experiment system and the schlieren experiment system are built to carry out research on the laminar premixed combustion characteristics of methane. The laminar burning velocity and the flame external field of methane/nitrogen/air were measured by the Bunsen burner method and the schlieren technique respectively, and the effects of equivalence ratio (ER) and nitrogen blending on the laminar burning velocity and the external field of the flame were investigated. The following conclusions are obtained through experiments: the equivalence ratio has an important influence on the laminar premixed combustion characteristics of the methane; and as the equivalence ratio increases, the laminar burning velocity increases first and then decreases, and the cone flame height decreases first and then increases; as well the external field of the flame starts to stabilize gradually. Nitrogen blending plays a negative role in the laminar burning velocity variation, at the same fime, the more nitrogen is blended, the more the laminar burning velocity decreases. The flame height increases with the increase of N₂ doping ratio, but the external flow field of the flame becomes more disordered and difficult to stabilize.