Simulation and modeling of soot formation and transport in turbulent flames

1403403木质素火焰的烟尘排放是一种污染物，危害健康，并影响传热。煤烟的形成是一个具有挑战性的问题，涉及到在其大小和时间的广泛条件下的非平凡的火焰相互作用。目前的研究重点是研究烟灰是如何在通常嵌入湍流中的实际火焰中形成的，比如喷气发动机和熔炉中的火焰。将开发基于计算机的模型，并对其进行验证。研究进展将通过出版物、演讲和网络进行交流。研究生和本科生将在计算燃烧方面接受指导和培训。小学生将通过火焰和流动演示，了解工程师的工作，让学生仔细观察燃烧如何推动社会。高中生将在本科生的指导下参加初级流体力学课程项目，小组定义问题，收集和分析数据，并提出结果。这项工作将通过应用三种模拟方法：一维湍流（ODT）、直接数值模拟（DNS）和大涡模拟（LES），在一项研究中解决湍流烟尘建模中的问题，以了解烟尘的形成和传输，并验证工程模拟中使用的模型。考虑了四个方面的任务：(1)在仿真代码中实现一致的烟尘模型；(2)进行ODT、DNS和LES模拟，以了解烟尘-火焰相互作用；(3)评价子网格烟尘模型；(4)面向中小学生的教育推广。然而，解析所有规模的唯一模拟方法是DNS，这对于实际流来说是非常昂贵的。对于DNS和LES，需要在一定尺度以下建立模型，因为无法获得精细尺度的信息。这项工作将使用ODT、DNS和LES来了解基本的烟尘-火焰-湍流-辐射相互作用，并量化烟尘传输模型。将ODT和LES与具有良好特征的实验射流火焰进行比较。这些模型的优点结合起来使用，可以弥补它们的缺点，并为需要进行研究的地方提供指导。

1403403LignellSoot emission from flames is a pollutant, a health hazard, and affects heat transfer. Soot formation is a challenging problem that involves non-trivial flame interactions over a wide range of conditions in their size and time. Efforts are focused on how soot forms in practical flames that are usually embedded in turbulence, such as those in jet engines and furnaces. Computer-based models will be developed and their validation will be carried out. Research advances will be communicated through publication, presentation, and on the web. Graduate and undergraduate students will be mentored and trained in computational combustion. Elementary school students will be introduced to what engineers do through flame and flow demonstrations that get students to look carefully at how combustion drives society. High school seniors will be mentored by undergraduate students as they participate in a junior-level fluid mechanics course project where groups define a problem, gather and analyze data, and present results.This work will address problems in turbulent soot modeling by applying three simulation approaches: one-dimensional turbulence (ODT), direct numerical simulation (DNS), and large eddy simulation (LES), in a single study to understand soot formation and transport, and to validate models used in engineering simulations. Four tasks are considered: (1) implementing consistent soot models into simulation codes; (2) performing ODT, DNS, and LES simulations to understand soot-flame interactions; (3) evaluating subgrid soot models; and (4) educational outreach to elementary and high school students. However, the only simulation approach that resolves all scales is DNS, which is prohibitively expensive for practical flows. For DNS and LES, models are needed below certain scales, because fine-scale information is not available. This work will use ODT, DNS, and LES to understand fundamental soot-flame-turbulence-radiation interactions, and quantify soot transport models. ODT and LES will be compared to well-characterized experimental jet flames. The strengths of these models, used together, complement their weaknesses and provide guidance as to where research needed.