Simulation and modeling of soot formation and transport in turbulent flames

Brigham Young University, Provo UT

Investigators

Abstract

1403403 Lignell Soot 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.