Spark ignition–controlled auto-ignition is a combustion strategy to overcome the challenges in a homogeneous charge compression ignition or controlled auto-ignition combustion which has a limited operation region and does not have any direct control of the combustion timing. However, the spark ignition–controlled auto-ignition combustion can result in a large cyclic variability due to two main distinctive combustion phases developing initially by flame propagation and following controlled auto-ignition combustion throughout an engine cycle. Characterization of combustion development is, therefore, required to maintain a stable engine operation under spark ignition–controlled auto-ignition combustion. In this research, experimental studies were carried out to investigate spark ignition–controlled auto-ignition combustion development at different spark advances and intake air temperatures. Combustion analyses were performed employing pressure-based heat release and mass fraction burn curve to determine the main combustion parameters along with transition points (corresponding to crank angles) to controlled auto-ignition and mass fraction burnt by flame propagation. The results reveal that transition point has a strong correlation with crank angle position where 10% of fuel mass consumed combustion phasing rather than mass fraction burnt by flame propagation at the same intake air temperature. The cycles with a higher mass fraction burnt by flame propagation can result from early flame development at the advanced spark timings (at −30 and −40 °CA) while the slow flame development at a spark timing of −20 °CA due to late transition point corresponding to crank angle occurred. Besides, it is also found that flame propagation phase more contributes to the cyclic variation in the whole combustion process.

中文翻译：

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在不同火花正时和进气温度下运行的汽油燃料火花点火控制自动点火发动机的燃烧发展

火花点火控制的自动点火是一种克服均质充量压缩点火或受控自动点火燃烧中挑战的燃烧策略，该燃烧具有有限的操作区域并且不能直接控制燃烧时间。然而，火花点火控制的自燃燃烧会导致较大的循环变化，这是由于两个主要的不同燃烧阶段最初由火焰传播和在整个发动机循环中跟随受控自燃燃烧产生。因此，需要对燃烧发展进行表征，以在火花点火控制的自燃燃烧下保持稳定的发动机运行。在这项研究中，进行了实验研究以研究在不同火花提前和进气温度下火花点火控制的自燃燃烧发展。使用基于压力的放热和质量分数燃烧曲线进行燃烧分析，以确定主要燃烧参数以及过渡点（对应于曲柄角）以控制自燃和通过火焰传播燃烧的质量分数。结果表明，过渡点与曲柄角位置有很强的相关性，在相同的进气温度下，10% 的燃料质量消耗燃烧定相而不是火焰传播燃烧的质量分数。通过火焰传播燃烧的具有较高质量分数的循环可能是由于提前点火正时（-30 和 -40 °CA）的早期火焰发展，而在-20 °CA 的点火正时由于延迟过渡导致火焰发展缓慢点对应的曲柄角出现。此外，还发现火焰传播阶段对整个燃烧过程的循环变化贡献更大。