The enhancement of the breakdown power during the spark discharge process has been proved to be beneficial for the flame kernel formation process under lean/diluted conditions. Such a strategy is realized by using a conventional transistor coil ignition system with an add-on capacitance in parallel to the spark plug gap in this paper. In practical application, the use of different ceramic material other than aluminum oxide can change the parasitic capacitance of the spark plug, achieving similar effect in terms of rescheduling the discharge energy released during the breakdown phase. Detailed research has been carried out to investigate the effect of the parallel capacitance and the cross flow velocity on the flame kernel formation and propagation process. With the increase in parallel capacitance, more spark energy is delivered during the breakdown phase, while less energy is released during the arc/glow phase. Shadowgraph images of the spark plasma reveal that the high-power spark discharge can generate a larger high-temperature area with enhanced electrically prompted turbulence under quiescent conditions, as compared with that using the conventional transistor coil ignition discharge strategy under the same condition. The breakdown enhanced turbulence of the high-power spark is proved to be beneficial for the flame kernel development, especially with the lean or exhaust gas recirculation diluted combustible mixtures, given that sufficient spark energy is available for the high-power spark strategy to successfully generate the breakdown event. The results of combustion tests under flow conditions reveal that the breakdown enhanced turbulence of the high-power spark tends to be overshadowed by the turbulence generated from the flow field, and both the increase in flow velocity and parallel capacitance contribute to the reduction in discharge duration of the arc/glow phase. Therefore, the benefits brought about by the high-power spark discharge tend to diminish with the intensification of flow velocity.

中文翻译：

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静止和流动条件下火花放电能量调度对点火的影响

火花放电过程中击穿功率的增强已被证明有利于稀/稀条件下的火焰核形成过程。这种策略是通过使用传统的晶体管线圈点火系统实现的，该系统具有与本文中的火花塞间隙并联的附加电容。在实际应用中，使用氧化铝以外的不同陶瓷材料可以改变火花塞的寄生电容，在重新安排击穿阶段释放的放电能量方面达到类似的效果。详细研究了并联电容和横流速度对火焰核形成和传播过程的影响。随着并联电容的增加，在击穿阶段提供更多的火花能量，而在电弧/辉光阶段释放的能量较少。火花等离子体的阴影图像显示，与在相同条件下使用传统晶体管线圈点火放电策略相比，高功率火花放电在静止条件下可以产生更大的高温区域和增强的电促湍流。大功率火花的击穿增强湍流被证明有利于火焰内核的发展，特别是在稀薄或废气再循环稀释的可燃混合物的情况下，考虑到足够的火花能量可用于大功率火花策略成功产生故障事件。流动条件下的燃烧试验结果表明，大功率火花击穿增强湍流往往被流场产生的湍流所掩盖，流速的增加和并联电容的增加都有助于减少放电持续时间电弧/辉光阶段。因此，大功率火花放电带来的好处往往随着流速的增加而减弱。