Partial fuel stratification (PFS) is a low temperature combustion strategy that can alleviate high heat release rates of traditional low temperature combustion strategies by introducing compositional stratification in the combustion chamber using a split fuel injection strategy. In this study, a three-dimensional computational fluid dynamics (CFD) model with large eddy simulations and reduced detailed chemistry was used to model partial fuel stratification at three different stratified conditions. The double direct injection strategy injects 80% of the total fuel mass at −300 CAD aTDC and the remaining 20% of the fuel mass is injected at three different timings of −160, −50, −35 CAD to create low, medium, and high levels of compositional stratification, respectively. The PFS simulations were validated using experiments performed at Sandia National Laboratories on a single-cylinder research engine that operates on RD5-87, a research-grade E10 gasoline. The objective of this study is to compare the performance of three different reduced chemical kinetic mechanisms, namely SKM1, SKM2, and SKM3, at the three compositional stratification levels and identify the most suitable mechanism to reproduce the experimental data. Zero-dimensional chemical kinetic simulations were also performed to further understand differences in performance of the three reduced chemical kinetic mechanisms to explain variations in CFD derived heat release profiles. The modeling results indicate that SKM3 is the most suitable mechanism for partial fuel stratification modeling of research-grade gasoline. The results also show that the autoignition event progresses from the richer to the leaner compositional regions in the combustion chamber. Notably, the leaner regions that have less mass per unit volume, can contribute disproportionately more toward heat release as there are more cells at leaner equivalence ratio ranges. Overall, this study illuminates the underlying compositional stratification phenomena that control the heat release process in PFS combustion.

部分燃料分层 (PFS) 是一种低温燃烧策略，它可以通过使用分流燃料喷射策略在燃烧室中引入成分分层来缓解传统低温燃烧策略的高热释放率。在这项研究中，具有大涡模拟和减少的详细化学的三维计算流体动力学 (CFD) 模型用于模拟三种不同分层条件下的部分燃料分层。双直喷策略在 -300 CAD aTDC 时喷射总燃料质量的 80%，其余 20% 的燃料质量在 -160、-50、-35 CAD 三个不同的正时喷射以产生低、中和分别具有高水平的成分分层。PFS 模拟通过在桑迪亚国家实验室对单缸研究发动机进行的实验进行验证，该发动机使用研究级 E10 汽油 RD5-87。本研究的目的是比较三种不同的还原化学动力学机制，即 SKM1、SKM2 和 SKM3，在三个成分分层水平上的性能，并确定最合适的机制来重现实验数据。还进行了零维化学动力学模拟，以进一步了解三种简化化学动力学机制的性能差异，以解释 CFD 派生的热释放曲线的变化。建模结果表明，SKM3 是最适合研究级汽油部分燃料分层建模的机制。结果还表明，自燃事件从燃烧室中的较富成分区域向较贫成分区域发展。值得注意的是，每单位体积具有较少质量的较贫区域可能会不成比例地更多地促进热释放，因为在较贫当量比范围内有更多细胞。总的来说，这项研究阐明了控制 PFS 燃烧中放热过程的潜在成分分层现象。