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首页> 外文期刊>Fuel >Effects of reactivity inhomogeneities on knock combustion in a downsized spark-ignition engine
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Effects of reactivity inhomogeneities on knock combustion in a downsized spark-ignition engine

机译：反应性不均匀性对缩小火花点火发动机爆震燃烧的影响

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摘要

The reactivity inhomogeneities are inevitably generated in the cylinder with the implementation of knock suppression strategies in downsized engines with direct-injection spark ignition. However, the mechanism of its influence on combustion has not yet been fully understood. A fundamental study was conducted by large eddy simulation to comprehensively study the effects of reactivity inhomogeneity formed by an independent variable of fuel stratification or temperature stratification on the in-depth mechanism of end-gas autoignition in a downsized spark ignition engine. The turbulent flame propagation is determined by an improved G-equation turbulent combustion model, and the detailed chemistry mechanism of a primary reference fuel is employed to observe the detailed reaction process in the end-gas autoignition process. Knock suppression results are observed in the temperature stratification case. In a large temperature gradient case, the premature autoignition timing caused by higher local temperature provides sufficient fresh gas for spontaneous combustion, leading to a better power performance compared to slight temperature gradient cases. Results of fuel stratification show that the knock is suppressed and gradually disappears with increasing Delta Phi. However, the subsequent reduction of peak pressure and the lengthening of combustion duration results in a terrible drop in power performance. The impact of flame propagation velocity dominates the pressure evolution compared to the effect of a highly local rich mixture reducing the ignition delay time under present conditions. This work will give an underlying understanding of the knock mechanism through different strategies.
机译：在汽缸中不可避免地产生反应性不均匀性，实施具有直接喷射火花点火的初级发动机中的爆震抑制策略。然而，其对燃烧影响的机制尚未得到完全理解。通过大涡模拟进行了一项基本研究，以全面地研究通过独立变量的燃料分层或温度分层形成的反应性不均匀性的影响，对缩小的火花点火发动机的最终气体自燃的深入机构。湍流火焰传播由改进的G方程湍流燃烧模型确定，主要参考燃料的详细化学机制用于观察到最终气体自燃过程中的详细反应过程。在温度分层壳体中观察到爆震抑制结果。在大的温度梯度外壳中，由较高局部温度引起的过早自燃定时为自发燃烧提供了足够的新鲜气体，导致更好的功率性能与轻微的温度梯度案例相比。燃料分层的结果表明，爆震被抑制并逐渐消失，随着δPHI增加。然而，随后降低了峰值压力和燃烧持续时间的延长导致功率性能的可怕下降。与高度局部富含混合物降低当前条件下的点火延迟时间的效果相比，火焰传播速度的影响主要占压力进化。这项工作将通过不同的策略给出对爆震机制的潜在理解。

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  • 来源
    《Fuel》 |2020年第15期|118317.1-118317.9|共9页
  • 作者

    Wang Ying; Wei Haiqiao; Zhou Lei; Zhang Xiaojun; Zhong Lijia;

  • 作者单位

    Tianjin Univ State Key Lab Engines Tianjin 300072 Peoples R China;

    Tianjin Univ State Key Lab Engines Tianjin 300072 Peoples R China;

    Tianjin Univ State Key Lab Engines Tianjin 300072 Peoples R China;

    Tianjin Univ State Key Lab Engines Tianjin 300072 Peoples R China;

    Tianjin Univ State Key Lab Engines Tianjin 300072 Peoples R China;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    Inhomogeneity; End-gas autoignition; Gasoline engine; Large eddy simulation;

    机译：不均匀性;终止气体自燃;汽油发动机;大涡模拟;

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