This work summarizes the numerical analysis of the effect of early fuel injection on the charge motion in a direct injection spark ignition engine concerning cyclic fluctuations of the flow field. The combination of the scale-resolving turbulence model “Scale Adaptive Simulation” and post-processing routines for vortex trajectory visualization allows for a detailed insight into the temporal resolved and cycle-dependent behavior of the charge motion. In the first part, a simplified engine set-up is presented and used as a validation case to ensure correct behavior of the turbulence model and post-processing routines. In the second part, the computational fluid dynamics model of the real engine is introduced. The application of the proposed vortex tracking algorithm is shown, and a short discussion about the transient behavior of the charge motion in this engine set-up is given. The third part describes the analysis of the influence of the fuel injection on the charge motion at different engine speeds from 1000 to 3000 r/min and variations of the intake pressure from 1 to 2 bar. Finally, the impact on different flow field properties at possible ignition timings is discussed. Changes in mean flow field quantities as well as in aerodynamic fluctuations are found as a consequence of fuel injection.

中文翻译：

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早期燃油喷射对直喷火花点火发动机充气运动影响的尺度解析模拟数值分析

这项工作总结了早期燃料喷射对直接喷射火花点火发动机中的充气运动影响的数值分析，涉及流场的循环波动。尺度解析湍流模型“尺度自适应模拟”和涡流轨迹可视化的后处理程序相结合，可以详细了解电荷运动的时间解析和循环相关行为。在第一部分中，介绍了一个简化的发动机设置，并将其用作验证案例，以确保湍流模型和后处理程序的正确行为。第二部分介绍了真实发动机的计算流体动力学模型。显示了所提出的涡流跟踪算法的应用，并简要讨论了该发动机设置中的充气运动的瞬态行为。第三部分描述了在 1000 到 3000 r/min 的不同发动机转速和 1 到 2 bar 的进气压力变化下燃油喷射对充气运动的影响分析。最后，讨论了在可能的点火正时对不同流场特性的影响。燃料喷射会导致平均流场量的变化以及空气动力学波动。讨论了在可能的点火正时对不同流场特性的影响。燃料喷射会导致平均流场量的变化以及空气动力学波动。讨论了在可能的点火正时对不同流场特性的影响。燃料喷射会导致平均流场量的变化以及空气动力学波动。