A systematic approach is formulated for the uncertainty analysis of kinetic parameters on combustion characteristics during skeletal reduction. The active subspace method together with sensitivity analysis is first employed to identify extreme low-dimensional active subspace of input parameter space and to facilitate the construction of response surfaces with small size of samples. An intermediate transition state during reduction is then defined such that the uncertainty change arising from uncertainty parameter truncation and reaction coupling during reduction can be decoupled and quantified. The approach is demonstrated in the reduction of a 55-species, 290-reaction dimethyl ether (DME) mechanism, with the rate constants characterized by independent lognormal distribution. Three representative skeletal mechanisms are identified for the uncertainty analysis, with each of the subsequent reduction yielding significant errors in the single-stage and/or two-stage DME-air auto-ignition process. Results show that sensitivity analysis can reduce the number of kinetic parameters from 290 down to 32, and the active subspace method can further identify a dominant active direction within this 32-dimensional subspace, which greatly facilitates the polynomial fitting for constructing the response surface of the ignition delay times. The uncertainty analysis with the polynomial chaos expansion method shows that the reduction from DME42 with 42 species to DME40 with 40 species has influential effect on the high-temperature reaction pathway; while the reduction from DME55 to DME42 and from DME40 to DME30 mainly affects the low-temperature pathway. In addition, the uncertainty change associated with parameter truncation is shown to be proportional to the change in the most active direction, which could further accelerate uncertainty analysis.

提出了一种系统的方法来对骨架还原过程中燃烧特性的动力学参数进行不确定性分析。主动子空间方法与灵敏度分析一起首先用于识别输入参数空间的极低维主动子空间，并有助于构建样本量较小的响应面。然后定义还原过程中的中间过渡状态，以使由还原过程中不确定性参数截断和反应耦合引起的不确定性变化可以解耦和量化。通过减少55种290反应的二甲醚（DME）机理证明了该方法，其速率常数具有独立的对数正态分布特征。确定了三种代表性的骨架机制用于不确定性分析，随后的每种还原都会在单级和/或两级DME-空气自动点火过程中产生重大误差。结果表明，灵敏度分析可以将动力学参数的数量从290个减少到32个，并且主动子空间方法可以进一步识别这个32维子空间内的主导主动方向，这极大地促进了多项式拟合的建立响应面。点火延迟时间。多项式混沌展开法的不确定性分析表明，从42种DME42还原为40种DME40对高温反应途径有影响。从DME55到DME42以及从DME40到DME30的还原主要影响低温途径。此外，与参数截断相关的不确定性变化与最活跃方向的变化成正比，这可能会进一步加快不确定性分析的速度。