丙烷/空气拉伸火焰传播稳定性实验研究

为了揭示空气中丙烷火焰传播特性，利用纹影系统记录了预混气体小能量点火条件下火焰形成与传播过程，得到了火焰表面的微观结构特征，分析了混合气体火焰的稳定性及其影响因素。结果表明:丙烷/空气混合物火焰发展过程及其表面微观特征与浓度直接相关；当混合物浓度接近爆炸上下限时，火焰扩展速率整体不大于0.5 m/s，燃烧区域向上漂浮，浮力成为影响火焰失稳的主导因素；当混合物浓度靠理论配比时，火焰呈规则球形扩展，火焰稳定性按照先减弱后增强的趋势发展，火焰表面褶皱的形成及演化规律是热扩散不稳定性和流体力学不稳定性共存与竞争的作用结果。

Experimental study on stability of propane/air stretched flame

In order to reveal the propagation characteristics of propane flame in air, the formation and propagation processes of premixed gas flame under the condition of small energy ignition were recorded by the schlieren system. The microstructure characteristics of flame surface were obtained, and the stability and its influencing factors of premixed gas flame were analyzed. The results showed that the development process and the surface microscopic characteristics of propane/air gas mixture flame were directly related to the concentration. When the mixture concentration was close to the upper and lower limits of explosion, the flame propagation velocity was not greater than 0.5 m/s on the whole, the combustion zone floated upward, and the buoyancy dominated the flame instability. When the concentration was close to the stoichiometric ratio, the flame expanded with a regular spherical shape, and the development trend of flame stability was first weakening and then strengthening. The formation and evolu-tion laws of the flame surface fold were the results of the coexistence and competition of thermal diffusion instabil-ity and fluid dynamics instability.