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供热系统，燃烧在世界经济中无处不在。尽管火焰普遍存在，但其潜在过程的复杂性仍然是科学家和工程师面临的挑战，特别是考虑到需要对有害排放、不受控制的火灾和减缓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，通常采用保留整体现象的基本特征的简化的物理和化学过程集。然而，这种方法往往过于简化了相关的燃烧属性，忽略了曲率和拉伸的影响，固有的现实世界的火焰。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燃烧和排烟特性的影响。拟议调查的结果将为燃烧模型开发和验证提供数据，以推进发电和供热技术，以维持美国使用清洁燃料的能源安全，并在可持续性方面保持全球领先地位。该项目还将允许来自CSUN（西班牙裔服务硕士机构）的学生参与尖端研究，并培养对未来科学和工程劳动力至关重要的技能。本文将详细研究非均匀弯曲非预混火焰结构的形貌和拉伸对其燃烧和排烟特性的影响。为此，本项目将对拉伸弯曲火焰进行研究，提供：(1)具有非均匀曲率的新型非预混逆流构型；(2)拉伸和非均匀曲率对火焰结构、稳定性、温度、烟尘形成和熄灭影响的实验数据；(3)描述曲率不均匀的拉伸非预混火焰的简化理论框架。采用二次曲面及其组合的新型非预混对流实验燃烧器将被开发出来，以产生与实际燃烧系统中火焰元素中观察到的火焰拓扑等效的火焰。颗粒图像测速法将用于流体流动表征，而烟灰和细丝高温法将用于确定烟灰形成和火焰温度。基于势流解和无限快化学的简化反应流模型将从理论上描述曲率对火焰整体特性的影响。在这个项目中提出的分析和配置将允许更好地理解曲率和拉伸对火焰现象的影响。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.