ERI: Stretch Effects on Combustion Characteristics of Flames with Non-Uniform Curvature

从火柴的火焰到最先进的发电和制热系统，燃烧在世界经济中无处不在。尽管普遍存在，但火焰中潜在过程的复杂性仍然对科学家和工程师构成挑战，特别是考虑到需要对有害排放、失控火灾和缓解气候变化制定更严格的法规。为了简化对实际燃烧器的分析，通常采用简化的物理化学过程集来保留整体现象的基本特征。然而，这种方法通常通过忽略真实世界火焰固有的曲率和拉伸的影响来过度简化相关的燃烧属性。因此，本项目的主要目标是深入了解地形和拉伸对非均匀弯曲火焰的燃烧和烟化特性的影响。拟议的调查结果将为燃烧模型的开发和验证提供数据，以推动发电和制热技术的发展，以维持美国使用清洁燃料的能源安全及其作为全球可持续发展领导者的地位。该项目还将允许来自CSUN的学生参与尖端研究，并开发对培养未来的科学和工程劳动力至关重要的技能。拟议的工作将详细说明地形和非均匀弯曲的非预混火焰结构对其燃烧和烟尘特性的影响。为此，本项目将对拉伸弯曲火焰进行研究，以提供：(1)具有非均匀曲率的新型非预混逆流结构；(2)详细描述拉伸和非均匀曲率对火焰结构、稳定性、温度、碳烟形成和熄灭影响的实验数据；(3)描述非均匀曲率拉伸非预混火焰的简化理论框架。采用二次曲面的新型非预混逆流实验燃烧器及其组合将被开发出来，以产生与在实际燃烧系统中观察到的火焰元素相同的火焰地形。粒子图像测速仪将用于流体流动的表征，而碳烟和细丝热法将用于确定碳烟的形成和火焰温度。建立基于势流解和无限快化学反应的简化反应流模型，从理论上描述曲率对整体火焰特性的影响。本项目中提出的分析和配置将允许更好地了解曲率和拉伸对火焰现象的影响。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

From the flame of a match to state-of-the-art power and heat generation systems, combustion is ubiquitous in the world economy. Despite its prevalence, the complexity of the underlying processes in a flame still represents a challenge for scientists and engineers, especially considering the need for more stringent regulations for harmful emissions, uncontrolled fires, and climate change mitigation. To simplify the analysis of practical burners, it is common to employ reduced sets of physical and chemical processes retaining essential characteristics of the overall phenomenon. However, such an approach often oversimplifies relevant combustion attributes by neglecting the effect of curvature and stretch inherent to real-world flames. Therefore, the primary goal of this project is to provide a deep understanding of the influence of topography and stretch on combustion and sooting characteristics of non-uniformly curved flames. Results from the proposed investigation will generate data for combustion model development and validation to advance power and heat generation technologies to sustain U.S. energy security using clean fuels and its position as a global leader in sustainability. The project will also allow students from CSUN, a Master’s Hispanic Serving Institution, to participate in cutting-edge research and develop skillsets critical for preparing the future workforce in science and engineering.The proposed work will detail the effect of topography and stretch of non-uniformly curved non-premixed flame structures in their combustion and sooting characteristics. To this end, this project will study stretched curved flames to provide: (1) novel non-premixed counterflow configurations with non-uniform curvature; (2) experimental data detailing stretch and non-uniform curvature influence on the flame structure, stability, temperature, soot formation, and extinction; (3) a simplified theoretical framework for the description of stretched non-premixed flames with non-uniform curvature. New non-premixed opposed-flow experimental burners employing quadric surfaces, and combinations thereof, will be developed to produce flame topographies equivalent to those observed in flame elements from practical combustion systems. Particle image velocimetry will be used for fluid flow characterization, whereas soot and thin filament pyrometry will be employed to determine soot formation and flame temperature. Simplified reacting flow models based on potential flow solutions and infinitely fast chemistry will be developed to describe curvature effects on overall flame characteristics theoretically. The analysis and configurations proposed in this project will allow a better understanding of curvature and stretch influence on flame phenomena.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.