甲烷/空气燃烧简化机理及其应用

Reduced Mechanism and Application of Methane/Air Combustion

为了找到适合活塞式发动机甲烷燃烧的化学反应动力学简化机理,从甲烷燃烧详细化学动力学机理出发,利用敏感性分析法,分析了包括多个不同组分的22步、39步、51步和58步基元反应的4种不同简化机理,并根据活塞式发动机的燃烧特点,将这4种简化机理应用于均匀搅拌反应器模型内甲烷/空气预混燃烧过程的计算中。研究结果表明:与详细反应机理的计算结果相比,当采用较少步数的22步基元反应的简化机理时,计算得到的燃烧温度结果误差较大,且出现明显的峰值后移现象,计算误差最大可达到12.5%。但随着采用基元反应简化机理的步数增加,这些误差明显减小。当采用58步基元反应的简化机理时,计算得到的出口温度和主要组分物质的量浓度随当量比变化的结果,与详细反应机理计算得到的结果基本吻合,最大误差不超过1%。这说明58步的基元反应简化机理包括了主要的反应式,计算结果具有足够的精度,可以很好地预测甲烷/空气预混燃烧现象。

In order to seek to appropriate reduced mechanism of chemical kinetics of methane combustion of piston engine,22-step,39-step,51-step and 58-step reduced mechanism which include multi different components and multi different reaction base units were analyzed by sensitivity analysis of detailed mechanism.According to characteristic of combustion of piston engine,these reduced mechanisms were applied to calculations of methane / air combustion in perfectly stirred reactor model. The calculation results show that comparied with the detailed mechanism calculation results,when 22-step reduced mechanism is used tocalculate the combustion temperature,the calculation error is large,the phenomenon of peak value moving back appears and the maximum calculation error will reach to 12. 5%. The calculation error will reduce when more high step reduced mechanism is used to calculate. When 58-step reduced mechanism is used to calculate the combustion temperature and main components concentration with equivalence ratio change,the calculation results are basicly identical with the one by using the detailed mechanism. The maximum calculation error is not exceeding 1%. It indicates that 58-step reduced mechanism includes main reaction equations. The calculation results have enough precision and the combustion phenomenon of advance mix methane / air can be forcasted.