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Obtention de modèles cinétiques réduits de combustion - Application à un mécanisme du kérosène

Abstract : Chemistry modelling of complex hydrocarbon mixtures (alkanes, aromatics and naphtenics) in a combustion process reconstituting industrial fuels requires hundreds species and thousands reactions. The associated system of differential equations is often too large and too stiff to be incorporated in industrial CFD (computational fluid dynamic) codes. So, a mechanism reduction must be considered. The main purpose of this work is to reduce, without damaging the initial predictive quality, a large detailed mechanism for kerosene (225 species among 3493 irreversible reactions) in perfectly stirred reactor (PSR) on a extended parametric condition range (pressure, equivalence ratio and reactor inlet temperature). The used method proceeds in a 3 steps: firstly the initial model is simplified by an elimination of useless species (with atomic flux analysis) then insignificant reactions are removed (with principal component analysis on rate matrix). Finally, the obtained skeletal mechanism is reduced by application of the quasi steady-state approximation for some species. Concentrations of those species are expressed according to the differential ones with an algebraic system. Inner-iteration technique, supplemented by a convergence accelerator, solves those algebraic expressions with a significant computational time saving. Each step of the reduction process has been automated in order to simplify and speed their use up. This methodology allows a detailed analysis of the significant pathways in the 3 reactant consumption as well as the sensitivity evaluation of implied reactions. Moreover, this reduction process leads, without particular kinetic knowledge, to the development of reduced schemes with computational time saving from a factor 15 (overall) to 50 (locally). More than 65% of species molar fractions are accurately reproduced with a relative deviation lower than 10% compared to the detailed model.
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Submitted on : Wednesday, October 26, 2011 - 3:27:20 PM
Last modification on : Tuesday, October 12, 2021 - 5:20:45 PM
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  • HAL Id : tel-00636023, version 1

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Jocelyn Luche. Obtention de modèles cinétiques réduits de combustion - Application à un mécanisme du kérosène. Chimie. Université d'Orléans, 2003. Français. ⟨tel-00636023⟩

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