Internal combustion engines are evolving to attain advanced combustion modes with higher percentage of compression ignition combustion. Homogeneous charge compression ignition is limited by load range and combustion stability, so hybrid combustion modes have emerged as a key research hotspot. In order to optimize hybrid combustion modes, combustion modes should be accurately identified. Therefore, this study introduces a new criterion and method to identify combustion modes. The results show that high compression ratio spark ignition engines are prone to autoignition, however, a trade-off relationship exists between high percentage of compression ignition combustion and the optimal combustion phase. As low percentage of compression ignition is favorable for engine efficiency, reduction of the combustion intensity should be considered. Under spark ignition assistance, both single-fuel and dual-fuel combustion exhibit a combustion mode where spark ignition and compression ignition occur simultaneously, which is defined as spark-assisted compression ignition combustion mode. The peak value (HP) for the second derivative of heat release rate at the onset of a combustion mode is strongly correlated with burning intensity and can be used to identify different combustion modes. The HP of spark ignition combustion is less than 1.5 J/deg3. Spark-assisted compression ignition combustion has an HP between 1.5 J/deg3 and 5.0 J/deg3, while the HP of premixed compression ignition combustion is at least 5.0 J/deg3.

中文翻译：

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一种在高压缩比火花点火发动机中分类燃烧模式的新准则和方法


内燃机正在发展，以实现具有更高比例的压缩点火燃烧的高级燃烧模式。均质装药压缩点火受载荷范围和燃烧稳定性的限制，因此混合动力燃烧模式已成为关键的研究热点。为了优化混合动力燃烧模式，应准确识别燃烧模式。因此，本研究引入了一种新的标准和方法来识别燃烧模式。结果表明，高压缩比火花点火发动机容易发生自燃，然而，高百分比的压缩点火燃烧与最佳燃烧阶段之间存在权衡关系。由于压缩点火百分比低有利于发动机效率，因此应考虑降低燃烧强度。在火花点火辅助下，单燃料和双燃料燃烧均表现出火花点火和压缩点火同时发生的燃烧模式，定义为火花辅助压缩点火燃烧模式。燃烧模式开始时热释放速率的二阶导数的峰值 （HP） 与燃烧强度密切相关，可用于识别不同的燃烧模式。火花点火燃烧的 HP 小于 1.5 J/deg3。火花辅助压燃燃烧的 HP 在 1.5 J/deg3 和 5.0 J/deg3 之间，而预混压燃燃烧的 HP 至少为 5.0 J/deg3。