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ENCIT 2016
16th Brazilian Congress of Thermal Sciences and Engineering
Comparison of different WSGG approaches in numerical simulation of a non-premixed turbulent methane-air flame
Submission Author:
Francis França , RS , Brazil
Co-Authors:
Aline Ziemniczak, Luís Gustavo Pires Rodrigues, Larissa Domingues Lemos, Fernando Pereira
Presenter: Aline Ziemniczak
doi://10.26678/ABCM.ENCIT2016.CIT2016-0379
Abstract
The Steady Laminar Diffusion Flamelet (SLDF) and the Weighted-Sum-of-Gray-Gases (WSGG) models are employed to solve numerically the Flame DLR-A, a non-premixed turbulent methane flame surrounded by a low-velocity air coflow, using ANSYS/Fluent code. The SLDF model allows for the separation of the interaction between chemical reactions and the flow field. Therefore, the laminar flamelet solutions can be pre-calculated and tabulated in a database, containing the mean reactive scalars, like temperature and species mass fractions, parameterized by few control variables, which in this study are the mixture fraction, its variance and dissipation rate. To generate the flamelet library, the turbulence-chemistry interaction is taken into account through presumed probability density functions (PDF) of these mean scalars. This approach efficiently reduces the computational time needed to achieve convergence of the solution. Radiation is taken into account through the WSGG model, in which the highly complex wavelength dependence of a non-gray gas is replaced by a small number of gray gases, for which the heat transfer rates are calculated independently. This study presents a comparison between Smith’s classical (Fluent) and correlations based on the HITEMP2010 database for the WSGG model (UDF). The coupling between the new WSGG correlations and the numerical code is made by a user-defined function (UDF). The numerical results are compared to experimental measurements in order to show the agreement level between the correlations for the WSGG model and the experimental data. The results show reasonable agreement with the measurements for temperature and species mass fractions for both approaches. However for the radiative heat flux distribution, the WSGG/Fluent tends to overpredict the radiation absorption in comparison with the WSGG/UDF.
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