CAREER: Measurements of Subgrid-Scale Scalar Mixing to Study Large-Eddy Simulation of Turbulent Combustion

职业：亚网格尺度标量混合测量以研究湍流燃烧的大涡模拟

• 批准号: 0093532
• 负责人: Chenning Tong
• 金额: --
• 依托单位: Clemson University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-04-01 至 2007-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0093532&HistoricalAwards=false
• 关键词: CAREER; Measurements; Subgrid; Scale; Scalar

This is an investigation of the subgrid-scale (SGS) mixing of conserved scalars which play a critical role in large-eddy simulation (LES) of nonpremixed turbulent combustion. Mixing of conserved scalars is generally considered to be dominated by a large-to-small-scale cascade process based on Kolmogorovs hypothesis. Current mixing models give qualitatively incorrect results for flows where the cascade process should dominate. Also, it is now recognized that large-scale velocity and scalar fields have significant influence on small-scale scalar mixing. In this project, the effects of the large-scale structure and of the cascade process on the filtered density function (the SGS distribution) of a conserved scalar is studied. High-resolution measurements of velocity and of conserved scalars are made in high-Reynolds-number turbulent jets with isotropic grid turbulence. Hot-wire and cold-wire arrays, particle image velocimetry (PIV), and planar laser Rayleigh scattering are used for the measurements. Issues in modeling the filtered density function of a conserved scalar and the filtered joint density function of a conserved scalar and its gradient are investigated. Both conventional statistical analyses and those based on conditional sampling and averaging are performed to investigate the effects of turbulent advection, turbulent strain and rotation, and molecular mixing on the filtered density function and other variables.

这是对守恒标量的亚网格尺度 (SGS) 混合的研究，它在非预混湍流燃烧的大涡模拟 (LES) 中发挥着关键作用。 保守标量的混合通常被认为是由基于柯尔莫哥洛夫假设的大到小规模级联过程主导的。 当前的混合模型对于级联过程应该占主导地位的流动给出了定性上不正确的结果。 此外，现在人们认识到大尺度速度场和标量场对小尺度标量混合具有显着影响。 在该项目中，研究了大规模结构和级联过程对保守标量的滤波密度函数（SGS 分布）的影响。 速度和守恒标量的高分辨率测量是在具有各向同性网格湍流的高雷诺数湍流射流中进行的。 测量采用热线和冷线阵列、粒子图像测速 (PIV) 和平面激光瑞利散射。 研究了对保守标量的滤波密度函数和保守标量的滤波联合密度函数及其梯度进行建模的问题。 进行传统统计分析以及基于条件采样和平均的统计分析，以研究湍流平流、湍流应变和旋转以及分子混合对过滤密度函数和其他变量的影响。