An investigation on flame-front instability in laminar and turbulent flames

层流和湍流火焰中火焰锋不稳定性的研究

• 批准号: 1827287
• 负责人: Chung Law
• 金额: $ 29.25万
• 依托单位: Princeton University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-06-15 至 2021-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1827287&HistoricalAwards=false
• 关键词: investigation; flame; front; instability; laminar

Combustion in modern high-performance engines, such as automotive and aircraft engines, occurs at high-pressure turbulent conditions. Engine efficiency and reliability strongly depend on flame dynamics, which can be intrinsically unstable in such extreme conditions. The proposed research will characterize the role of flame-front instabilities on flame propagation in engine-relevant conditions. This knowledge is needed for optimizing modern engines, especially at high pressures and high turbulent conditions. Using a unique dual-chamber vessel, which allows high-pressure investigations, the experiments will be targeted to extend our current knowledge on flame-front instabilities in both laminar and turbulent flames. Results from this study can be extended to other problems, such as large-scale fire-whirl dynamics in wildland and urbane fires, which are intrinsically turbulent even the combustion is at atmospheric pressure, in addition to the astrophysical phenomena of the supernova explosion with cosmic intensity. This project will engage graduate and undergraduate students who will be exposed to advanced diagnostics while studying the basic combustion physics and chemistry.The proposed program aims to understand and quantify the fundamental dynamics of different modes of intrinsic flame-front instabilities of propagating flames in either quiescent or well-defined turbulent environments. Such an understanding is rather immature at present but is required for the further advance in the design and optimization of modern combustion engines. The investigation includes experimentation on spark-ignited, spherical flames at high- and constant-pressure conditions using high-speed high-resolution optical diagnostics. The uniqueness of this study is the well-controlled, well-characterized, high-pressure environment. In such environments, prominent hydrodynamic cellular/wrinkling flame-front structures are manifested and can be precisely quantified using optical diagnostics in unprecedented details. The understanding is facilitated by acquiring high-fidelity experimental data and by quantitatively defining and assessing various stability parameters. This work will characterize global and local length scales for different modes of flame propagation under conditions of isolated instability, isolated turbulence, and their coupled influences. Since the proposed study includes both experimental and theoretical investigations, it will provide the essential synergistic experience in the design and data interpretation of both components, leading to advances in the knowledge of high-pressure turbulent combustion systems.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.

现代高性能发动机（例如汽车和飞机发动机）中的燃烧发生在高压湍流条件下。发动机的效率和可靠性在很大程度上取决于火焰动力学，而火焰动力学在这种极端条件下本质上是不稳定的。拟议的研究将描述火焰前锋不稳定性在发动机相关条件下对火焰传播的作用。这些知识对于优化现代发动机是必要的，特别是在高压和高湍流条件下。使用一个独特的双室容器，它允许高压调查，实验将有针对性地扩展我们目前的知识，在层流和湍流火焰火焰的火焰前不稳定性。从这项研究的结果可以扩展到其他问题，如大规模的火旋风动力学在荒地和城市火灾，这是内在的湍流，即使燃烧是在大气压下，除了宇宙强度的超新星爆炸的天体物理现象。该项目将吸引研究生和本科生，他们将在学习基本燃烧物理和化学的同时接触到先进的诊断学，该项目旨在了解和量化在静止或明确定义的湍流环境中传播火焰的不同模式的固有火焰前缘不稳定性的基本动力学。这样的理解目前还相当不成熟，但对于现代内燃机的设计和优化的进一步发展是必需的。调查包括实验火花点火，球形火焰在高和恒压条件下使用高速高分辨率光学诊断。这项研究的独特之处在于控制良好、特征鲜明、高压的环境。在这样的环境中，突出的流体动力学细胞/燃烧火焰前锋结构的表现，并可以精确地量化使用光学诊断前所未有的细节。通过获取高保真度的实验数据，并通过定量定义和评估各种稳定性参数，促进了理解。这项工作将描述孤立的不稳定性，孤立的湍流，以及它们的耦合影响的条件下，不同的火焰传播模式的全球和局部的长度尺度。由于拟议的研究包括实验和理论研究，它将在两个组件的设计和数据解释方面提供必要的协同经验，从而提高高压湍流燃烧系统的知识水平。该奖项反映了NSF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。

项目成果

Self-acceleration and global pulsation in expanding laminar H2−O2−N2 flames

• DOI: 10.1103/physrevfluids.4.043201
• 发表时间: 2019-04
• 期刊: Physical Review Fluids
• 影响因子: 2.7
• 作者: J. Huo;A. Saha;Tao Shu;Zhuyin Ren;C. Law

Local statistics of laminar expanding flames subjected to Darrieus–Landau instability

• DOI: 10.1016/j.proci.2020.06.118
• 发表时间: 2020-08
• 作者: Zirui Liu;Vishnu R Unni;Swetaprovo Chaudhuri;C. Law;A. Saha

Self-turbulization in cellularly unstable laminar flames

细胞不稳定层流火焰中的自湍流

• DOI: 10.1017/jfm.2021.330
• 发表时间: 2021
• 期刊: Journal of Fluid Mechanics
• 影响因子: 3.7
• 作者: Liu, Zirui;Unni, Vishnu R.;Chaudhuri, Swetaprovo;Sui, Ran;Law, Chung K.;Saha, Abhishek
• 通讯作者: Saha, Abhishek

A cellular automata model for expanding turbulent flames

膨胀湍流火焰的元胞自动机模型

• DOI: 10.1063/5.0018947
• 发表时间: 2020
• 期刊: Chaos: An Interdisciplinary Journal of Nonlinear Science
• 作者: Unni, Vishnu R.;Law, Chung K.;Saha, Abhishek
• 通讯作者: Saha, Abhishek