N2对甲烷-空气预混气体爆炸火焰传播稳定性的影响

为了探究N2惰化作用对甲烷-空气预混气体火焰稳定性的影响，利用自主搭建的1m3球形爆炸实验系统，实验研究了球形火焰稳定性及其影响因素。通过研究结果表明，仅改变甲烷浓度：贫燃条件下，热-质扩散不稳定性与流体力学不稳定性的共同作用是火焰前期失稳的主要因素，在甲烷浓度在化学计量比附近时，火焰稳定性最弱；继续增大甲烷浓度，热扩散因素开始制约D-L不稳定性对火焰表面扰动的影响，因此甲烷浓度为13%的火焰稳定性仅略大于10%的甲烷浓度。随着甲烷浓度向爆炸极限靠近时，可以明显观察到火焰上浮，浮力不稳定性成为主导因素。改变氮气添加比：相较于热-质扩散不稳定性，流体力学不稳定性对氮气添加比的变化更为敏感，添加比大于8%时，在流体力学不稳定性影响下，火焰稳定性迅速增强。

Influence of N2 on the flame stability of methane-air premixed gas

In order to investigate the effect of the methane-dilute gas premix ratio on flame stability under the effect of N₂ inerting, the spherical flame stability and its influencing factors are analyzed by using the experimental system of medium-sized spherical closed vessel explosion built independently. Through the results of the study, it is shown that changing only the methane concentration: the mutual enhancement of heat-mass diffusion instability and hydrodynamic instability is the main factor of flame instability at low concentration conditions, and the flame stability is weakest near the methane concentration of 9.5%, and continuing to increase the methane concentration, hydrodynamic instability becomes the main factor of dominant flame instability, but under the limitation of heat-mass diffusion instability factor methane concentration of 13% flame stability is only slightly greater than that of 10% methane concentration. As the methane concentration approaches the explosion limit, flame uplift is clearly observed and buoyancy instability becomes the dominant factor. Changing the nitrogen addition ratio: Compared with the heat-mass diffusion instability, the hydrodynamic instability is more sensitive to the change of the nitrogen addition ratio, and the flame stability increases rapidly under the influence of hydrodynamic instability for addition ratios greater than 8%.