燃烧反应机理全局性简化及骨架机理优化

Global Reduction for Combustion Reaction Mechanism and Skeletal Mechanism Optimization

燃烧基元反应速率系数存在着一定的不确定性,会影响各基元反应对燃烧特性参数的贡献,传统图解简化法统计基元反应中各组分贡献大小也会受此影响,使组分之间的耦合强度存在着一定的不确定性.为此拟开展基于燃烧反应动力学速率系数不确定性下的机理简化和优化.首先在速率系数不确定性参数空间内均匀采集1000个可能性详细机理样本,然后应用直接关系图解法(DRG)对机理样本进行简化,并对排除的组分进行统计和排序,最终根据概率大小削减模型;其次应用全局敏感性方法判断其重要反应机理,对其中较为灵敏的反应进一步优化,最终得到可以预测相对准确的简化机理.

There exist uncertainties in the reaction rate coefficients of combustion mechanisms,which will affect the contribution of different reactions to the combustion characteristic parameters.Moreover,these uncertainties will also influence the statistics of contributions by different species in the reactions when the reduction method based on relation graph is employed,causing the coupling degree between species to be uncertain.In the present work,the combustion mechanism is simplified and optimized with the consideration of uncertainties in the reaction rate coefficients.First,1 000 possible detailed mechanisms are obtained by uniform sampling in the uncertain parametric domain of rate coefficients.Then,the directed relation graph(DRG)method is applied to simplify these detailed mechanisms,and the removed species are counted and ranked.Finally,the model is reduced according to the probability.In addition,the global sensitivity analysis(GSA)method is applied to identify the key reaction in the skeletal mechanisms,and those with higher sensitivity are further optimized.In this way,the simplified mechanism with higher prediction accuracy can be obtained.