Mathematical Modeling of Combustion Phenomena at the Microscale

微尺度燃烧现象的数学模型

• 批准号: 0708588
• 负责人: Moshe Matalon
• 金额: $ 14.63万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-15 至 2010-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0708588&HistoricalAwards=false
• 关键词: Mathematical; Modeling; Combustion; Phenomena; Microscale

Matalon0708588 The objective of the project is to enhance physicalunderstanding of the intricate processes occurring in combustionat the microscale, in order to support and guide ongoingexperimental efforts in this area. Mathematically, the problemsrequire finding solutions to coupled, highly nonlinear partialdifferential equations, further complicated by inevitabletemporal variations, multi-scale processes, and nontrivialboundaries. Tractable problems require judicious modelingefforts in order to capture the main features of the phenomenaunder consideration. The simplified models are addressed usingappropriate analytical or numerical strategies in order toprovide solutions that enable comparing the theoreticalpredictions with experimental observations. The investigatorexamines two sets of problems. The first set is associated withpremixed combustion in an excess-enthalpy combustor where the hotcombustion products are recirculated to heat up the freshreactants, thus enhancing the burning rate and heat output. Thesecond set of problems is associated with nonpremixed combustionin a confined slot, where the mixing zone and the resultingdiffusion flame spread over the entire length of the reactorchannel. The goal is to study the structure, properties anddynamics of flames in such configurations and identify conditionsfor steady burning, onset of instabilities, flashback or blowoff,and flame extinguishment. Combustion is a subject of great economical and societalconcern. Despite the continuing search for alternative energysources, combustion still provides the majority of the energyconsumed today. It is therefore important to ensure thatcombustion processes are utilized in the most efficient way, andin such a way as to minimize undesirable effects on theenvironment. Recent development in the field of microscalecombustion has been motivated by the increased need for smallerscale and high density power sources and by the fact thathydrocarbon fuels have enormous advantages over batteries interms of energy storage per unit mass. There are, however,important issues that need to be addressed in order to renderthis technology practical and efficient. Beyond the difficultiesassociated with fabrication, fundamental questions concerned withthe underlying combustion physics need to be overcome. Thedevelopment of combustion systems at the microscale requiresdeeper understanding at the fundamental level of fluid flow inmicrochannels, heat and mass transport at the small scale,combustion in small volumes and complex geometries, thermal andchemical properties of the wall materials, and fluid-wallinteractions. Mathematical modeling plays an important roletowards this goal; it provides means to explain experimentalobservations and identify the physical mechanisms responsible forthese observations. The investigator, building on his earliercontributions to fluid mechanics and chemically reacting flows,studies the peculiarities of combustion at the microscale inorder to improve physical understanding of these phenomena. Byguiding and supporting the ongoing experimental efforts theproject has an immediate effect on advancements of this newtechnology.

该项目的目标是在微观尺度上加强对燃烧中复杂过程的物理理解，以支持和指导这一领域正在进行的实验工作。在数学上，这些问题需要找到耦合的、高度非线性的偏微分方程组的解，而不可避免的临时变化、多尺度过程和非平凡边界使问题变得更加复杂。容易处理的问题需要明智的建模工作，以捕捉所考虑的现象的主要特征。使用适当的分析或数值策略来处理简化模型，以便提供能够将理论预测与实验观测相比较的解决方案。这项研究提出了两组问题。第一套装置与过量焓燃烧室中的预混燃烧有关，在该燃烧室中，热燃烧产物被再循环以加热新反应物，从而提高燃烧速度和热输出。第二组问题与受限缝隙中的非预混燃烧有关，在受限缝隙中，混合区和由此产生的扩散火焰蔓延到整个反应堆通道长度。目标是研究这种构型下火焰的结构、性质和动力学，并确定稳定燃烧、不稳定开始、闪回或喷出和火焰熄灭的条件。燃烧是一个极具经济意义和社会意义的话题。尽管不断寻找替代能源，燃烧仍然提供了今天所消耗的大部分能源。因此，重要的是确保以最有效的方式利用燃烧过程，并将对环境的不良影响降至最低。微型燃烧领域的最新发展是由于对小型和高密度电源的需求的增加，以及氢碳燃料在单位质量的储能方面比电池具有巨大的优势。然而，有一些重要的问题需要解决，以便使这项技术实用和有效。除了与制造有关的困难外，还需要克服与基本燃烧物理有关的基本问题。微尺度燃烧系统的发展需要对微通道内的流体流动、小尺度下的传热传质、小体积和复杂几何形状的燃烧、壁面材料的热和化学性质以及流壁相互作用等基本问题有更深入的了解。数学建模在实现这一目标方面发挥了重要作用；它提供了解释实验观测并确定造成这些观测的物理机制的手段。这位研究人员在他早期对流体力学和化学反应流动的贡献的基础上，在微观尺度上研究了燃烧的特性，以提高对这些现象的物理理解。通过指导和支持正在进行的实验工作，该项目对这项新技术的进步产生了立竿见影的效果。