The hydrodynamic instability characteristics of non-adiabatic N₂-diluted n-butane/air flames generated on McKenna burner were investigated experimentally under atmosphere pressure. In order to capture the quantitative structure of cellular flames, planar laser induced fluorescence technology (OH-PLIF and CH₂O-PLIF) was employed, as well as the chemiluminescence imaging was used to record flame morphology directly. The results show that the hydrodynamic instability of stoichiometric (Φ = 1.0) n-butane/air flames can be significantly enhanced by N₂ dilution. In addition, the increased mixture flow velocity and the reduced equivalence ratio of lean mixtures will enhance hydrodynamic instability. Moreover, the observed flame morphologies are connected wrinkles instead of independent-cells with lean and stoichiometric mixtures. It is probable that the wrinkled flames mainly caused by hydrodynamic instability cannot induce the extinction of high-temperature oxidant reaction in concave regions solely due to the weakened effect of preferential diffusion. The instability mechanism analysis shows that, the remarkably reduced local flame speed and the much deformed local flow field ahead of n-butane/air/N₂ dilution flames by increasing N₂ dilution ratio play an important role in enhancing hydrodynamic instability. It also indicates that the heat loss reduced more in concave regions than in convex regions toward unburnt mixtures is helpful to enhance the suppression effect of hydrodynamic instability.

在大气压下通过实验研究了在 McKenna 燃烧器上产生的非绝热 N ₂稀释的正丁烷/空气火焰的流体动力学不稳定性特性。为了捕捉细胞火焰的定量结构，采用平面激光诱导荧光技术（OH-PLIF和CH ₂ O-PLIF），并利用化学发光成像直接记录火焰形态。结果表明， N ₂可以显着增强化学计量（Φ = 1.0）正丁烷/空气火焰的流体动力学不稳定性稀释。此外，增加的混合物流速和减少的贫混合物当量比将增强流体动力学的不稳定性。此外，观察到的火焰形态是连接的皱纹，而不是具有稀薄和化学计量混合物的独立单元。主要由流体动力学不稳定性引起的皱纹火焰可能不会仅仅由于优先扩散的减弱作用而导致凹区高温氧化反应的消失。失稳机理分析表明，在正丁烷/空气/N ₂稀释火焰之前，通过增加N ₂使局部火焰速度显着降低，局部流场变形较大。稀释比在增强流体动力学不稳定性方面起着重要作用。这也表明，对于未燃烧的混合物，凹区的热损失比凸区减少的更多，这有助于增强水动力不稳定性的抑制效果。