Publications

Filtered mass density functions (FMDFs) of mixture fraction and temperature are studied by analyzing experimental data obtained from one-dimensional Raman/Rayleigh/LIF measurements of nonpremixed CH4/H2/N2 turbulent jet flames at Reynolds numbers of 15,200 and 22,800 (DLR-A and -B). The experimentally determined FMDFs are conditioned on the Favré filtered values of the mixture fraction and its variance. Filter widths are selected as fixed multiples of the experimentally determined dissipation length scale at each measurement location. One-dimensional filtering using a top-hat filter is performed to obtain the filtered variables used for conditioning. The FMDFs are obtained by binning the mass and filter kernel weighted samples. Emphasis is placed on the shapes of the FMDFs in the fuel-rich, fuel-lean, and stoichiometric intervals for the Favré filtered mixture fraction, and low, medium, and high values for the Favré filtered mixture fraction variance. It is found that the FMDFs of mixture fraction are unimodal in samples with low mixture fraction variance and bimodal in samples with high variance. However, the FMDFs of mixture fraction at the smallest filter size studied are unimodal for all values of the variance. The FMDFs of temperature are unimodal in samples with low mixture fraction variance, and either unimodal or bimodal, depending on the mixture fraction mean, in samples with high variance. The influence of the filter size and the jet Reynolds number on the FMDFs is also considered. © 2008 The Combustion Institute.

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This paper focuses on the application of the large eddy simulation (LES) technique to a swirling particle-laden flow in a model combustion chamber. A series of calculations have been performed and compared directly with detailed experimental measurements. The computational domain identically matches the laboratory configuration, which effectively isolates effects related to dilute particle dispersion and momentum coupling. Results highlight the predictive capabilities of LES when implemented with the appropriate numerics, grid resolution (as dictated by the class of models employed) and well-defined boundary conditions. The case study provides a clearer understanding of the effectiveness and feasibility of current state-of-the-art models and a quantitative understanding of relevant modeling issues by analyzing the characteristic parameters and scales of importance. The novel feature of the results presented is that they establish a baseline level of confidence in our ability to simulate complex flows at conditions representative of those typically observed in gas-turbine (and similar) combustors. © 2006 The Combustion Institute. Published by Elsevier Inc. All rights reserved.