Experimental Investigation of Multiscalar Subgrid-Scale Mixing and Turbulence-Chemistry Interaction

1333489 Tong提出的研究解决了使用大涡模拟（LES）预测湍流燃烧的问题，重点是多标量亚网格尺度（SGS）混合和湍流化学相互作用。 多个反应标量的混合及其与火焰中化学的相互作用涉及复杂的过程，并且还没有很好地理解。 该研究将系统地研究多标量的SGS混合，为改进SGS混合模型提供必要的理解。 选择湍流同轴射流进行多标量研究，其中每个射流和同轴流具有不同燃料和空气的可变混合物，这些燃料和空气被发送到包含空气的背景中以提供不同的混合配置。 这种同轴射流允许研究三标量SGS混合，混合物分数，和温度在驾驶湍流部分预混火焰。 这项研究使用了新的实验和分析工具，首次在湍流火焰中产生混合物分数和温度场的二维图像。 预计这些结果将显着推进物理学的理解至关重要的一个主要的模型改进SGS混合模型能够预测多标量SGS混合和双折射化学相互作用。 对SGS物理学的理解对于其他研究领域也很重要，包括湍流和一系列非线性现象之间的相互作用。 拟议的研究要求为研究生和本科生提供一个综合的教育和研究计划，参与规划和进行实验，并参加技术会议。

1333489TongThe proposed research addresses issues in using large-eddy simulation (LES) to predict turbulent combustion, focusing on multiscalar subgrid-scale (SGS) mixing and turbulence-chemistry interaction. Mixing of multiple reactive scalars and its interaction with chemistry in flames involve complex processes and are not well understood. The proposed research will systematically investigate SGS mixing of multiple scalars to provide the understanding necessary for improving SGS mixing models. Turbulent coaxial jets are chosen for the multiscalar study where each of the jet and coaxial streams have variable mixture of different fuels and air issued into the background containing air to provide different mixing configurations. This coaxial jet allows study of three-scalar SGS mixing, mixture fraction, and temperature in piloted turbulent partially premixed flames. This research uses novel experiments and analysis tools, producing for the first time two-dimensional images of mixture fraction and temperature fields in a turbulent flame. The results are expected to significantly advance the understanding of the physics essential for a major model improvement in SGS mixing models capable of predicting multiscalar SGS mixing and turbulence-chemistry interaction. The understanding of the SGS physics gained will be important for other research areas as well, including interactions between turbulence and a range of nonlinear phenomena. The proposed research calls for an integrated education and research program for graduate and undergraduate students, with involvement in both planning and conducting experiments and participating in technical conferences.