Abstract Ignition initiation by a turbulent hot jet involves complex transport and chemical processes with disparate and sensitive time scales. Its understanding is important for improved ignition in advanced and novel combustion engines and in ignition avoidance for explosion safety measures. This study is aimed at the modeling of turbulent hot jet ignition of stoichiometric hydrogen-air mixture with fast chemistry and short chemical time scales relative to the large-scale mixing time scales. The evolution of jet mixture fraction in the near-field shear layer of a suddenly-starting turbulent jet is analytically modeled and calibrated by large-eddy simulation of the reacting fluid. When integrated with a correlation for instantaneous chemical induction time, the model estimates the radial location and the timing of ignition as the jet travels in the streamwise direction. The estimation includes accounting for the role of the scalar dissipation rate in the suppression of ignition. The radial location of ignition migrates towards the jet centerline with time, migrating faster for higher injection temperatures and much slower for leaner ambient fuel-air ratios. The limitations of the present model are investigated by assessing the regions of mixing layer where strong diffusive transport collocates with the high production rate of active radicals. To complete the perspective into analytic modeling of transient jet ignition, other limitations associated with turbulent fluctuations and jet composition are discussed, as well as the role of near-field ignition relative to ignition at the jet tip or head vortex ring.

中文翻译：

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注入热气近场点燃H2/空气的解析与数值研究

摘要 湍流热射流引发的点火涉及复杂的传输和化学过程，具有不同且敏感的时间尺度。它的理解对于改进先进和新型内燃机的点火以及避免爆炸安全措施的点火非常重要。本研究旨在模拟化学计量的氢-空气混合物的湍流热射流点火，具有快速化学和相对于大规模混合时间尺度的短化学时间尺度。突然启动的湍流射流的近场剪切层中射流混合物分数的演变通过反应流体的大涡模拟进行分析建模和校准。当与瞬时化学诱导时间的相关性结合时，当射流沿流向运动时，该模型估计径向位置和点火时间。估计包括考虑标量耗散率在抑制点火中的作用。随着时间的推移，点火的径向位置向着喷气中心线迁移，对于较高的喷射温度迁移得更快，而对于更稀薄的环境燃料空气比迁移得更慢。通过评估混合层的区域，其中强扩散传输与活性自由基的高生产率并存，研究了本模型的局限性。为了完成瞬态射流点火分析建模的观点，讨论了与湍流波动和射流成分相关的其他限制，