Sustainable and low-emission combustion is in need of novel schemes to enhance combustion efficiency and control, to meet up with new emission standards and comply with varying quality of renewable fuels. Plasma actuation is a promising candidate to achieve this goal but few detailed experiments have been carried out that target how specific combustion and plasma related species are affected by the coupling of plasma and combustion chemistry. Atomic hydrogen is such a species that here is imaged by using the two photon planar laser induced fluorescence (TPLIF) technique as an atmospheric pressure methane-air flame is actuated by nanosecond repetitively pulsed (NRP) discharges. Atomic hydrogen is observed both in the flame and in the discharge channel and plasma actuation results in a wide modification of the flame shape. A local 50% increase of fluorescence occurs at the flame front where it is crossed by the discharge. Atomic hydrogen in the discharge channel in the fresh-gases is found to decay with a time constant of about 2.4 μs. These results provide new insights on the plasma flame interaction at atmospheric pressure that can be further used for cross-validation of numerical calculations.

中文翻译：

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纳秒重复脉冲放电辅助下层流甲烷-空气火焰中原子氢的飞秒双光子激光诱导荧光成像

可持续和低排放的燃烧需要新的方案来提高燃烧效率和控制，以满足新的排放标准并符合不同质量的可再生燃料。等离子体驱动是实现这一目标的有希望的候选者，但很少有详细的实验针对特定燃烧和等离子体相关物质如何受等离子体和燃烧化学的耦合影响。原子氢是这样一种物质，这里通过使用双光子平面激光诱导荧光 (TPLIF) 技术成像，因为大气压甲烷-空气火焰由纳秒重复脉冲 (NRP) 放电驱动。在火焰和放电通道中都观察到原子氢，等离子体驱动导致火焰形状的广泛改变。荧光的局部增加 50% 发生在与放电交叉的火焰前沿。发现新鲜气体中放电通道中的原子氢以大约 2.4 μs 的时间常数衰减。这些结果为大气压下等离子体火焰相互作用提供了新的见解，可进一步用于数值计算的交叉验证。