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.

这是对保守标量的亚网格尺度（SGS）混合的研究，该标量在非构成湍流燃烧的大涡模拟（LES）中起着关键作用。 通常认为，保守标量的混合被认为是基于Kolmogorovs假设的大型至小规模的级联进程所占据的。 当前的混合模型给出了级联过程应占主导地位的流量的定性不正确结果。 同样，现在已经认识到，大规模的速度和标量场对小规模标量混合有重大影响。 在这个项目中，研究了大规模结构和级联过程对保守标量的过滤密度函数（SGS分布）的影响。 速度和保守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德式湍流喷气机中进行的。 热线和冷线阵列，粒子图像速度法（PIV）和平面激光雷利散射用于测量。 研究了保守标量的过滤密度函数和保守标量及其梯度的过滤关节密度函数的问题。 进行常规统计分析以及基于条件采样和平均的分析，以研究湍流对流，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。