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

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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.