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

1333489同拟用大涡模拟(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。火焰中多个反应标量的混合及其与化学的相互作用涉及复杂的过程，目前还没有很好的理解。拟议的研究将系统地研究多标量的SGS混合，以提供对改进SGS混合模型所需的理解。湍流同轴射流被选择用于多标量研究，其中每个射流和同轴流都具有不同的燃料和空气的不同混合，这些混合被释放到含有空气的背景中以提供不同的混合构型。这种同轴射流可以研究引导的部分预混湍流火焰中的三标量SGS混合、混合分数和温度。这项研究使用了新的实验和分析工具，首次产生了湍流火焰中混合物分数和温度场的二维图像。这一结果有望极大地促进对SGS混合模式重大模式改进的物理理解，该模式能够预测多标量SGS混合和湍流-化学相互作用。对SGS物理的理解对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。这项拟议的研究呼吁为研究生和本科生建立一个综合的教育和研究计划，参与计划和进行实验，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.