Abstract The medium-speed dual-fuel engine has become popular in the marine industry for its advantages of fulfilling the stringent emission regulations and relative affordability of natural gas. In such engines, the ignition process importantly influences the subsequent combustion processes and engine performance. This work developed a phenomenological micro-pilot ignition model with a minimal number of tuning parameters aiming to improve the understanding of the ignition event and enable better control of the dual-fuel engine. The model comprises of a spray and a chemistry submodel to accurately capture the interaction between the direct injection of a small amount of diesel fuel (called micro-pilot) and a two-stage ignition of the diesel fuel mixed with the surrounding reactive charge in relatively low temperature. A 1D transient spray model is adapted to reproduce the micro-pilot spray characteristics by assuming a realistic trapezoidal fuel injection profile and the varying discharge coefficient during the transient spray period. The chemical reactions are modeled with a 0D transient flamelet approach based on an opposed flow reactor. The model is validated using three sets of experimental data, namely ECN Spray A (constant volume chamber), RCEM with optical accessibility, and finally, medium-speed dual-fuel engine. Quantitatively good predictions of the spray formation, ignition delay, and ignition location over broad conditions ranging from the conventional diesel ignition to the micro-pilot ignition in the dual-fuel engine are demonstrated. Finally, the developed model is used to explore the characteristics of micro-pilot ignition under conditions relevant to the medium-speed dual-fuel engines.

中文翻译：

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中速双燃料发动机现象学微引燃模型

摘要 中速双燃料发动机因其满足严格的排放法规和天然气相对可负担性的优势而在船舶工业中受到欢迎。在此类发动机中，点火过程对随后的燃烧过程和发动机性能产生重要影响。这项工作开发了一种现象学微引燃点火模型，其调整参数数量最少，旨在提高对点火事件的理解并更好地控制双燃料发动机。该模型由喷雾和化学子模型组成，以准确捕捉少量柴油的直接喷射（称为微先导）与柴油与周围反应性装料混合的两级点火之间的相互作用。低温。一维瞬态喷雾模型适用于通过假设真实的梯形燃料喷射剖面和瞬态喷雾期间变化的排放系数来重现微先导喷雾特性。化学反应是用基于对流反应器的 0D 瞬态小火焰方法建模的。该模型使用三组实验数据进行验证，即 ECN Spray A（恒定容积室）、具有光学可达性的 RCEM，最后是中速双燃料发动机。展示了在从传统柴油点火到双燃料发动机中的微引燃点火的广泛条件下对喷雾形成、点火延迟和点火位置的定量预测。最后，