Experimental study of local extinction in laminar and turbulent flames

层流和湍流火焰中局部消光的实验研究

• 批准号: 1552074
• 负责人: Michael Renfro
• 金额: $ 19.37万
• 依托单位: University of Kentucky Research Foundation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-01 至 2018-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1552074&HistoricalAwards=false
• 关键词: Experimental; study; local; extinction; laminar

1336184RenfroIn many practical combustors, heat is released by chemical reactions in relatively thin flame sheets. Turbulence in the flow of fuel and air in the combustor lead to fluctuations in velocity that perturb the flame sheet and increase the transfer of heat away from the flame. When these fluctuations are sufficiently large, the heat loss can be too high compared to the heat released by the flame resulting in local extinction. A local extinction event leaves a hole in the flame sheet that can lead to complete extinction of the flame. In many applications extinction is a significant limitation to the operation of the combustor, while in other applications extinction can be desired to quench a flame. In either case, physical understandings of the mechanisms that cause extinction are needed. This project seeks a fundamental understanding of the interactions of velocity and flame sheets that cause local extinction such that more accurate models of flame limits and the response of flame holes can be generated. The intellectual merit of the work focuses on a detailed understanding of the impact that velocity fluctuations in turbulent flames have on heat transfer from flames sheets as well as the impact of these changes to the flame's chemical heat release. The experimental and computational project will utilize an optically-accessible combustor that has been designed to create local extinction in a flame sheet enabling a detailed study using laser diagnostics. The measurements will be used to develop models describing extinction that can have broader impact on industrial design tools. The research will involve the participation of graduate and undergraduate students, who will be trained in fundamental combustion theory and application of optical measurements.

在许多实际燃烧室中，热量是通过化学反应在相对较薄的火焰片中释放出来的。燃烧室中燃料和空气流动的湍流会导致速度的波动，从而扰乱火焰薄片并增加从火焰中转移的热量。当这些波动足够大时，与导致局部消光的火焰释放的热量相比，热量损失可能太高。局部消光事件会在火焰薄片上留下一个洞，从而可能导致火焰完全熄灭。在许多应用中，熄火是燃烧器操作的重要限制，而在其他应用中，可能需要消光来熄灭火焰。在任何一种情况下，都需要对导致物种灭绝的机制有物理上的了解。该项目寻求对引起局部消光的速度和火焰片的相互作用有一个基本的了解，以便能够产生更准确的火焰极限和火孔响应的模型。这项工作的学术价值在于详细了解湍流火焰中的速度波动对火焰薄片的热传递的影响，以及这些变化对火焰化学热释放的影响。这个实验和计算项目将利用一种光学可接近的燃烧器，这种燃烧器被设计成在火焰薄片中产生局部消光，从而能够使用激光诊断进行详细研究。这些测量将被用来开发描述灭绝的模型，这些模型可能会对工业设计工具产生更广泛的影响。这项研究将涉及研究生和本科生，他们将接受基本燃烧理论和光学测量应用方面的培训。