Nonlinear Dynamics of Premixed and Diffusion Flames

拟议工作的目标是推导和分析描述火焰动力学的数学模型。这些模型将从质量守恒定律、动量守恒定律和能量守恒定律出发，用渐近方法系统地推导出来，并用解析和数值方法进行分析。建议识别包含真实燃烧系统足够细节的数学模型，并对这些模型进行分析，以便对在更简单的情况下物理和化学过程如何相互作用有基本的了解。为了检验模型和它们的预测，将与实验记录进行比较。这些数学问题涉及非线性演化方程和火焰不稳定性的非线性方面。拟议的工作的目的是对燃烧问题中发生的复杂过程有基本的了解，这些问题在各种工程应用中都会遇到。提高我们对燃烧现象的基本理解可以为应用研究提供新的方向，并导致更好的燃烧系统设计。将要调查的问题与在实验室中观察到但尚未完全理解的现象有关。拟议的工作将解决三类问题：第一类涉及开放空间和受限环境中预混火焰的演变，其中火焰和流体动力场之间的耦合效应是主要感兴趣的。预混火焰的研究具有重要的技术意义，可直接应用于内燃机过程。第二类问题涉及非预混燃烧或扩散火焰中的不稳定性，其理论研究才刚刚出现。出于安全原因，在炉子中最好使用非预混条件，而在这里的柴油发动机中，液体燃料在燃烧室中蒸发，提供与空气一起燃烧的必要燃料蒸汽。第三类问题涉及火焰在易燃液体上的传播，其中液体和气相中的组合行为决定了火焰的动力学。火焰蔓延到易燃液体的意外溢出，或石化行业中遇到的“流动液体火灾”，可能会成为火灾危险。

0072588MatalonThe objective of the proposed work is to derive and analyze mathematical models that describe the dynamics of flames. The models will be derived systematically from the conservation laws of mass, momentum and energy by means of asymptotic methods and analyzed using analytical and numerical methods. It is proposed to identify mathematical models that contain enough details of the real combustion systems and analyze these models in order to gain basic understanding on how the physical and chemical processes interact in the simpler circumstances. Comparison with the experimental record will be performed in order to test the models and their predictions. The mathematical problems involve nonlinear evolution equations and nonlinear aspects of flame instabilities.The objective of the proposed work is to gain fundamental understanding in the complex processes occurring in combustion problems, problems that are encountered in various engineering applications. Improving our fundamental understanding of combustion phenomena could suggest new directions for applied research and lead to a better design of combustion systems. The problems that will be investigated are related to phenomena that have been observed in the laboratory but are not yet completely understood. The proposed work will address three classes of problems: The first class is concerned with the evolution of premixed flames in open space and in confined environments, where the coupled effects between the flame and the hydrodynamic field is of primary interest. Studies of premixed flames have significant technological importance and are directly applicable to internal combustion engines processes. The second class of problems is concerned with instabilities in non-premixed combustion, or diffusion flames, for which theoretical studies are only now emerging. Non-premixed conditions are favored in furnaces for safety reasons and in diesel engines here the liquid fuel evaporates in the combustion chamber providing the necessary fuel vapor that burns with air. The third class of problems is concerned with flame spread over flammable liquids, where the combined behaviors in the liquid and gas phases determine the flame dynamics. Flame spread over an accidental spillage of a flammable liquid, or a "running liquid fire" encountered in petrochemical industries, can become a fire hazard.