二甲醚/空气预混合气燃烧特性

Combustion Characteristics of DME/Air Premixed Mixtures

利用定容燃烧弹研究了不同当量比和初始压力下的二甲醚/空气预混合气的燃烧特性,并基于准维双区模型计算了二甲醚/空气预混合气燃烧特征参数.研究结果表明:在各初始压力条件下,化学计量比附近的混合气压力升高率和混合气质量燃烧速率最大.对于稀混合气和当量比混合气,火焰传播速率随初始压力的降低而增加;而对于浓混合气,火焰传播速率随初始压力的降低而降低.最高燃烧压力出现在化学计量比附近而与初始压力无关.对于给定的当量比,最高燃烧压力随初始压力的增加而明显增加.在化学计量比附近,燃烧持续期和火焰发展期最短且基本上不随初始压力变化.

Combustion characteristics of dimethyl ether/air premixed mixtures were studied in a constant volume bomb under various equivalence ratios and initial pressures. Meanwhile, a two-zone model was proposed for predicting combustion parameters based on pressure data. The study shows that the mixtures with the stoichiometric equivalence ratio have the maximum normalized mass burning rate and maximum pressure rise rate. For the lean mixtures and the mixture with the sto-ichiometric equivalence ratio, the flame propagation speed increases with the decrease of initial pressure, while for the rich mixture, the flame propagation speed decreases with the decrease of initial pressure. The maximum combustion pressure occures at the stoichiometric equivalence ratio regardless of initial pressure. For a given equivalence ratio, the maximum combustion pressure increases remarkably with the increase of initial pressure. The shortest combustion duration and flame development duration occur at the stoichiometric equivalence ratio and remain almost unchanged with the investigated initial pressures