采用改进的PREMIX模型及“化学爆炸模式分析(CEMA)”方法，对二甲醚(DME)球形扩散火焰的熄火机理进行数值诊断，分析环境氧气摩尔分数(XO2)及详细基元反应对熄火极限的影响，利用“爆炸因子”和“分岔因子”的概念，确定控制DME球形扩散火焰熄火的关键反应动力学因素。结果表明：DME冷焰具有比热焰更宽的可燃范围；冷焰对XO2的敏感性弱很多，热焰中具有正特征值的CEM首次出现在最高温度处；在熄火极限附近，CEM的特征值变为虚数，说明熄火伴随着振荡；热焰的熄火主要由小分子所参与的高温反应所控制，而冷焰熄火主要由大分子所参与的低温反应所控制。

The modified PREMIX model and chemical explosive mode analysis (CEMA) method were used to perform a numerical diagnostic analysis on the extinction mechanism of dimethyl ether (DME) spherical diffusion flame.The dependence of flame extinction limit on the ambient oxygen mole fraction(XO2) and detailed chemical kinetics was emphasized in this paper.Additionally,the concepts of “explosive index” and “bifurcation index” were employed to specify the governing reactions for the DME flame extinction.The results show that DME spherical diffusion cool flame has a much broadened flammability range compared to the hotflame counterpart.The cool flames are rather insensitive to the variation of XO2.The positive CEM mode firstly appears at the temperaturepeaking location.In the nearextinction range,eigenvalue of the CEM mode becames a complex number,indicating the tendency of oscillatory instability in this condition.The hotflame extinction is governed by the hightemperature reaction involving small species,whil the coolflame extinction is controlled by lowtemperature reactions involving large hydrocarbons.

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国家自然科学基金(51706027)；重庆市自然科学基金(cstc2019jcyj-msxmX0584)