• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Combustion and Flame >Direct numerical simulation of a temporally evolving air-dodecane jet at low-temperature diesel-relevant conditions
【24h】

Direct numerical simulation of a temporally evolving air-dodecane jet at low-temperature diesel-relevant conditions

机译：在低温柴油相关条件下随时间变化的空气/正十二烷射流的直接数值模拟

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

We present a direct numerical simulation of a temporal jet betweenn-dodecane and diluted air undergoing spontaneous ignition at conditions relevant to low-temperature diesel combustion. The jet thermochemical conditions were selected to result in two-stage ignition. Reaction rates were computed using a 35-species reduced mechanism which included both the low- and high-temperature reaction pathways. The aim of this study is to elucidate the mechanisms by which low-temperature reactions promote high-temperature ignition under turbulent, non-premixed conditions. We show that low-temperature heat release in slightly rich fuel regions initiates multiple cool flame kernels that propagate towards very rich fuel regions through a reaction-diffusion mechanism. Although low-temperature ignition is delayed by imperfect mixing, the propagation speed of the cool flames is high: as a consequence, high-temperature reactions in fuel-rich regions become active early during the ignition transient. Because of this early start, high-temperature ignition, which occurs in fuel-rich regions, is faster than homogeneous ignition. Following ignition, the high-temperature kernels expand and engulf the stoichiometric mixture-fraction iso-surface which in turn establish edge flames which propagate along the iso-surface. The present results indicate the preponderance of flame folding of existing burning surfaces, and that ignition due to edge-flame propagation is of lesser importance.. Finally, a combustion mode analysis that extends an earlier classification [1] is proposed to conceptualize the multi-stage and multi-mode nature of diesel combustion and to provide a framework for reasoning about the effects of different ambient conditions on diesel combustion.
机译：我们提出了正十二烷与在与低温柴油燃烧有关的条件下自燃的稀薄空气之间的时间射流的直接数值模拟。选择喷射热化学条件以导致两阶段点火。使用35种还原机制计算反应速率，其中包括低温和高温反应途径。这项研究的目的是阐明在湍流，非预混合条件下，低温反应促进高温点火的机理。我们表明，在稍富燃料区中的低温热释放引发了多个冷火焰核，这些核通过反应扩散机制向非常富燃料区传播。尽管由于不完全混合而延迟了低温点火，但冷火焰的传播速度很高：因此，燃料丰富区域中的高温反应会在点火瞬变的早期活跃。由于这种早期启动，发生在燃料丰富区域的高温点火比均匀点火要快。点燃后，高温籽粒膨胀并吞没化学计量的混合分数等值面，进而形成沿等值面传播的边缘火焰。目前的结果表明，现有燃烧表面的火焰折叠占优势，而边缘火焰传播引起的点火的重要性较小。最后，提出了一种扩展了较早分类的燃烧模式分析[1]，以概念化多火焰燃烧。柴油燃烧的阶段性和多模式性质，并为推理不同环境条件对柴油燃烧的影响提供了框架。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号