EAGER: Experimental investigation of physical-space scalar structure and unresolved mixing to improve large-eddy simulation of turbulent combustion

EAGER：物理空间标量结构和未解决的混合的实验研究，以改进湍流燃烧的大涡模拟

• 批准号: 2208136
• 负责人: Chenning Tong
• 金额: $ 29.68万
• 依托单位: Clemson University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2208136&HistoricalAwards=false
• 关键词: EAGER; Experimental; investigation; physical; space

This project investigates a key process, turbulent mixing, in combustion. Turbulent combustion occurs and plays an important role in many engineering applications, such as jet engines, gas turbine generators, internal combustion engines, and chemical processing plants. The modern design process of such devices needs to employ numerical modeling to evaluate design choices and to optimize design parameters. However, the current state-of-the art modeling approach, large-eddy simulation (LES), despite decades of research efforts, still does not have the accuracy needed for advanced engineering design, primarily because the unresolved mixing process is not well predicted. Previous efforts to understand mixing had been partially hampered by the predominant LES approach. This research will investigate mixing using the novel LES approach developed by S. B. Pope as the framework, which overcomes the limitations of the traditional approach. The new approach, however, also poses challenges in experimental techniques and data analysis methods. The researchers will employ a new laser diagnostic technique and new statistical analysis method. The research will significantly advance the understanding of the fundamental physics in turbulent combustion, which will potentially enable development of combustion models with sufficient accuracy for designing high-performance and low emission engineering devices, which will have a positive impact on society and the environment. The understanding of the physics gained will also benefit other research areas involving interactions between turbulence and strongly nonlinear phenomena, such as chemical engineering processes, atmospheric physics, atmospheric chemistry, and environment systems.This project investigates the physical-space structure and the unresolved mixing as well as their interaction with chemistry using the recently developed self-conditioned fields LES approach (Pope 2010) as the framework, which overcomes the limitations of the filtering LES approach. The researchers will conduct experiments in turbulent non-reactive coaxial jets and in jet flames. Two-dimensional images will be obtained in coaxial jets. A new photo-dissociation-based diagnostic technique and new statistical analysis method will be used. Direct numerical simulation of a Sydney flame (Thorsten et al. 2019), which contains 3D images, will complement the experiments. Researchers will analyze the physical-space scalar structure and its representation in the self-conditioned joint PDF and the unclosed mixing terms in its transport equation. The results provide a basis for investigating the mixing of mixture fraction and temperature in piloted turbulent partially premixed (Sandia) flames. The researchers will analyze the effects of the physical-space scalar structure on the self-conditioned scalar JMDF and the unclosed mixing terms. The project is the first to use the novel self-conditioned LES approach as the framework. It is also the first time true two-dimensional images of mixture fraction and temperature with resolved dissipation scales are obtained in turbulent hydrocarbon flames without major compromising assumptions. The results are expected to significantly advance the understanding of the unresolved physics essential for developing improved mixing models capable of accurately predicting multiscalar mixing and turbulence-chemistry interaction.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

该项目调查了一个关键过程，即燃烧中的湍流混合。湍流燃烧发生并在许多工程应用中起重要作用，例如喷气发动机，燃气轮机发电机，内燃机和化学加工厂。此类设备的现代设计过程需要采用数值建模来评估设计选择并优化设计参数。然而，尽管数十年的研究工作仍然没有高级工程设计所需的准确性，但当前的最新建模方法，大涡模拟（LES），主要是因为未解决的混合过程并未得到很好的预测。以前的理解混合的努力已被主要的LES方法所部分阻碍。这项研究将使用S. B. Pope作为该框架开发的新型LES方法研究混合，从而克服了传统方法的局限性。然而，新方法在实验技术和数据分析方法中也带来了挑战。研究人员将采用一种新的激光诊断技术和新的统计分析方法。这项研究将大大提高对湍流燃烧中基本物理的理解，这将有可能使燃烧模型具有足够准确的燃烧模型，以设计高性能和低排放工程设备，这将对社会和环境产生积极影响。 The understanding of the physics gained will also benefit other research areas involving interactions between turbulence and strongly nonlinear phenomena, such as chemical engineering processes, atmospheric physics, atmospheric chemistry, and environment systems.This project investigates the physical-space structure and the unresolved mixing as well as their interaction with chemistry using the recently developed self-conditioned fields LES approach (Pope 2010) as the framework, which overcomes the limitations of the filtering LES 方法。研究人员将在湍流非反应性同轴喷气机和喷气火焰中进行实验。二维图像将在同轴喷气机中获得。将使用一种新的基于照片的诊断技术和新的统计分析方法。悉尼火焰的直接数值模拟（Thorsten等，2019），其中包含3D图像，将补充实验。研究人员将分析物理空间标量结构及其在自我条件的关节PDF中的表示以及其传输方程中未锁定的混合项。该结果为研究混合物分数和温度的混合而定为湍流（Sandia）火焰的混合物提供了基础。研究人员将分析物理空间标量结构对自我调节标量JMDF和未封闭的混合项的影响。该项目是第一个使用新颖的自我调节方法作为框架的项目。这也是第一次在没有重大损害假设的湍流碳氢化合物火焰中获得混合分数和温度和温度的真正二维图像。预计该结果将显着提高人们对开发改进的混合模型至关重要的未解决的物理学的理解，该模型能够准确地预测多层型混合和湍流化学的相互作用。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子优点和更广泛影响的评估来通过评估来获得支持的。