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ENCIT 2016
16th Brazilian Congress of Thermal Sciences and Engineering
Computation of the radiative heat flux from a laminar methane/air flame obtained with the gray gas and the weighted-sum-of-gray-gases models
Submission Author:
Francis França , RS , Brazil
Co-Authors:
Luís Gustavo Pires Rodrigues, Fernando Pereira
Presenter: Luís Gustavo Pires Rodrigues
doi://10.26678/ABCM.ENCIT2016.CIT2016-0375
Abstract
In this study the weighted-sum-of-gray-gases (WSGG) and the gray gas (GG) models are coupled with the software ANSYS/Fluent to predict the radiation heat transfer of an open laminar coflowing methane/air flame. The problem is first solved only for the combustion process and after convergence the radiation modeling is included. Combustion is modeled by the laminar finite-rate model considering a detailed chemical mechanism (DRM19) and appropriate thermal and transport properties. Numerical results for both decoupled and coupled radiation/combustion are compared with experimental measurements. Both WSGG and GG models are implemented with correlations obtained with the HITEMP2010 spectral database. The absorption coefficient for the GG model is calculated as a function of local temperature and concentration of the participating species (carbon dioxide and water vapor). The coupling between Fluent and the spectral models is made by means of user-defined functions (UDF). Results point that the GG model is less expensive computationally than the WSGG model, but gives less accurate results. The WSGG model can predict both qualitatively and quantitatively the radiative heat flux with good accuracy and proved itself a viable alternative to predict radiation heat transfer in spite of its relative simplicity.
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