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.

本文研究了在非预混湍流燃烧大涡模拟中起关键作用的守恒标量的亚网格尺度（SGS）混合。 基于柯尔莫哥洛夫假设，守恒标量的混合通常被认为是由大到小的级联过程所主导。 目前的混合模型给出了定性的不正确的结果，级联过程应该占主导地位的流量。 此外，现在人们认识到，大尺度的速度和标量场有显着的影响，小尺度标量混合。 在这个项目中，大尺度结构和级联过程对保守标量的过滤密度函数（SGS分布）的影响进行了研究。 高分辨率的速度和守恒标量的测量在高雷诺数湍流射流与各向同性网格湍流。 热线和冷线阵列，粒子图像测速（PIV），和平面激光瑞利散射用于测量。 研究了守恒标量的滤波密度函数和守恒标量及其梯度的滤波联合密度函数的建模问题。 传统的统计分析和那些基于条件采样和平均进行调查的影响，湍流平流，湍流应变和旋转，和分子混合的过滤密度函数和其他变量。